diff --git a/basis/bootstrap/stage2.factor b/basis/bootstrap/stage2.factor
index 4eb2a1db91..4d566a288d 100644
--- a/basis/bootstrap/stage2.factor
+++ b/basis/bootstrap/stage2.factor
@@ -16,13 +16,6 @@ SYMBOL: bootstrap-time
     vm file-name os windows? [ "." split1-last drop ] when
     ".image" append resource-path ;
 
-: do-crossref ( -- )
-    "Cross-referencing..." print flush
-    H{ } clone crossref set-global
-    xref-words
-    xref-generics
-    xref-sources ;
-
 : load-components ( -- )
     "include" "exclude"
     [ get-global " " split harvest ] bi@
@@ -68,8 +61,6 @@ SYMBOL: bootstrap-time
 
     (command-line) parse-command-line
 
-    do-crossref
-
     ! Set dll paths
     os wince? [ "windows.ce" require ] when
     os winnt? [ "windows.nt" require ] when
diff --git a/basis/help/crossref/crossref-docs.factor b/basis/help/crossref/crossref-docs.factor
index ae227fde89..7f243ec764 100644
--- a/basis/help/crossref/crossref-docs.factor
+++ b/basis/help/crossref/crossref-docs.factor
@@ -17,8 +17,3 @@ HELP: xref-article
 { $values { "topic" "an article name or a word" } }
 { $description "Sets the " { $link article-parent } " of each child of this article." }
 $low-level-note ;
-
-HELP: unxref-article
-{ $values { "topic" "an article name or a word" } }
-{ $description "Clears the " { $link article-parent } " of each child of this article." }
-$low-level-note ;
diff --git a/basis/help/crossref/crossref.factor b/basis/help/crossref/crossref.factor
index b791a4b124..46f9561605 100644
--- a/basis/help/crossref/crossref.factor
+++ b/basis/help/crossref/crossref.factor
@@ -1,4 +1,4 @@
-! Copyright (C) 2005, 2008 Slava Pestov.
+! Copyright (C) 2005, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: arrays definitions generic assocs math fry
 io kernel namespaces prettyprint prettyprint.sections
@@ -12,9 +12,6 @@ IN: help.crossref
 : article-children ( topic -- seq )
     { $subsection } article-links ;
 
-M: link uses
-    { $subsection $link $see-also } article-links ;
-
 : help-path ( topic -- seq )
     [ article-parent ] follow rest ;
 
@@ -22,10 +19,7 @@ M: link uses
     article-children [ set-article-parent ] with each ;
 
 : xref-article ( topic -- )
-    dup >link xref dup set-article-parents ;
-
-: unxref-article ( topic -- )
-    >link unxref ;
+    dup set-article-parents ;
 
 : prev/next ( obj seq n -- obj' )
     [ [ index dup ] keep ] dip swap
diff --git a/basis/help/help.factor b/basis/help/help.factor
index d20e06b6c6..956bc220e1 100644
--- a/basis/help/help.factor
+++ b/basis/help/help.factor
@@ -156,10 +156,7 @@ help-hook [ [ print-topic ] ] initialize
     error get (:help) ;
 
 : remove-article ( name -- )
-    dup articles get key? [
-        dup unxref-article
-        dup articles get delete-at
-    ] when drop ;
+    articles get delete-at ;
 
 : add-article ( article name -- )
     [ remove-article ] keep
@@ -167,7 +164,6 @@ help-hook [ [ print-topic ] ] initialize
     xref-article ;
 
 : remove-word-help ( word -- )
-    dup word-help [ dup unxref-article ] when
     f "help" set-word-prop ;
 
 : set-word-help ( content word -- )
diff --git a/basis/tools/continuations/continuations.factor b/basis/tools/continuations/continuations.factor
index 3e28c5925f..1ac4557ec4 100644
--- a/basis/tools/continuations/continuations.factor
+++ b/basis/tools/continuations/continuations.factor
@@ -4,7 +4,7 @@ USING: threads kernel namespaces continuations combinators
 sequences math namespaces.private continuations.private
 concurrency.messaging quotations kernel.private words
 sequences.private assocs models models.arrow arrays accessors
-generic generic.standard definitions make sbufs ;
+generic generic.standard definitions make sbufs tools.crossref ;
 IN: tools.continuations
 
 <PRIVATE
diff --git a/basis/tools/crossref/crossref-docs.factor b/basis/tools/crossref/crossref-docs.factor
index f49ac7ea76..99d1257f31 100644
--- a/basis/tools/crossref/crossref-docs.factor
+++ b/basis/tools/crossref/crossref-docs.factor
@@ -1,15 +1,57 @@
-USING: help.markup help.syntax words definitions prettyprint ;
+USING: help.markup help.syntax words definitions prettyprint
+tools.crossref.private math quotations assocs ;
 IN: tools.crossref
 
-ARTICLE: "tools.crossref" "Cross-referencing tools" 
+ARTICLE: "tools.crossref" "Definition cross referencing"
+"Definitions can answer a sequence of definitions they directly depend on:"
+{ $subsection uses }
+"An inverted index of the above:"
+{ $subsection get-crossref }
+"Words to access it:"
+{ $subsection usage }
+{ $subsection smart-usage }
+"Tools for interactive use:"
 { $subsection usage. }
+{ $subsection vocab-uses. }
+{ $subsection vocab-usage. }
 { $see-also "definitions" "words" "see" } ;
 
 ABOUT: "tools.crossref"
 
+HELP: uses
+{ $values { "defspec" "a definition specifier" } { "seq" "a sequence of definition specifiers" } }
+{ $description "Outputs a sequence of definitions directory called by the given definition." }
+{ $notes "The sequence might include the definition itself, if it is a recursive word." }
+{ $examples
+    "We can ask the " { $link sq } " word to produce a list of words it calls:"
+    { $unchecked-example "\ sq uses ." "{ dup * }" }
+} ;
+
+HELP: crossref
+{ $var-description "A graph whose vertices are definition specifiers and edges are usages. See " { $link "graphs" } ". This variable is reset to " { $link f } " every time a definition is added or removed. Call " { $link get-crossref } " to lazily construct the graph instead of using this variable directly." } ;
+
+HELP: get-crossref
+{ $values { "crossref" assoc } }
+{ $description "Outputs the cross-referencing index, mapping definitions to usages, building it first if necessary." }
+{ $notes "This word is used to implement " { $link usage } " and " { $link usage. } "." } ;
+
+HELP: crossref-def
+{ $values { "defspec" "a definition specifier" } }
+{ $description "Adds a vertex representing this definition, along with edges representing dependencies to the " { $link crossref } " graph." }
+$low-level-note ;
+
+HELP: usage
+{ $values { "defspec" "a definition specifier" } { "seq" "a sequence of definition specifiers" } }
+{ $description "Outputs a sequence of definitions that directly call the given definition." }
+{ $notes "The sequence might include the definition itself, if it is a recursive word." } ;
+
 HELP: usage.
 { $values { "word" "a word" } }
 { $description "Prints an list of all callers of a word. This may include the word itself, if it is recursive." }
 { $examples { $code "\\ reverse usage." } } ;
 
+HELP: quot-uses
+{ $values { "quot" quotation } { "assoc" "an assoc with words as keys" } }
+{ $description "Outputs a set of words referenced by the quotation and any quotations it contains." } ;
+
 { usage usage. } related-words
diff --git a/basis/tools/crossref/crossref-tests.factor b/basis/tools/crossref/crossref-tests.factor
index d08a17fd02..26c6c4e597 100755
--- a/basis/tools/crossref/crossref-tests.factor
+++ b/basis/tools/crossref/crossref-tests.factor
@@ -11,3 +11,40 @@ M: integer foo + ;
 
 [ t ] [ integer \ foo method \ + usage member? ] unit-test
 [ t ] [ \ foo usage [ pathname? ] any? ] unit-test
+
+! Issues with forget
+GENERIC: generic-forget-test-1 ( a b -- c )
+
+M: integer generic-forget-test-1 / ;
+
+[ t ] [
+    \ / usage [ word? ] filter
+    [ name>> "integer=>generic-forget-test-1" = ] any?
+] unit-test
+
+[ ] [
+    [ \ generic-forget-test-1 forget ] with-compilation-unit
+] unit-test
+
+[ f ] [
+    \ / usage [ word? ] filter
+    [ name>> "integer=>generic-forget-test-1" = ] any?
+] unit-test
+
+GENERIC: generic-forget-test-2 ( a b -- c )
+
+M: sequence generic-forget-test-2 = ;
+
+[ t ] [
+    \ = usage [ word? ] filter
+    [ name>> "sequence=>generic-forget-test-2" = ] any?
+] unit-test
+
+[ ] [
+    [ M\ sequence generic-forget-test-2 forget ] with-compilation-unit
+] unit-test
+
+[ f ] [
+    \ = usage [ word? ] filter
+    [ name>> "sequence=>generic-forget-test-2" = ] any?
+] unit-test
\ No newline at end of file
diff --git a/basis/tools/crossref/crossref.factor b/basis/tools/crossref/crossref.factor
index 36ccaadc98..feaddc8194 100644
--- a/basis/tools/crossref/crossref.factor
+++ b/basis/tools/crossref/crossref.factor
@@ -1,9 +1,84 @@
 ! Copyright (C) 2005, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: assocs definitions io io.styles kernel prettyprint
-sorting see ;
+USING: words assocs definitions io io.pathnames io.styles kernel
+prettyprint sorting see sets sequences arrays hashtables help.crossref
+help.topics help.markup quotations accessors source-files namespaces
+graphs vocabs generic generic.standard.engines.tuple threads
+compiler.units init ;
 IN: tools.crossref
 
+SYMBOL: crossref
+
+GENERIC: uses ( defspec -- seq )
+
+<PRIVATE
+
+GENERIC# quot-uses 1 ( obj assoc -- )
+
+M: object quot-uses 2drop ;
+
+M: word quot-uses over crossref? [ conjoin ] [ 2drop ] if ;
+
+: seq-uses ( seq assoc -- ) [ quot-uses ] curry each ;
+
+M: array quot-uses seq-uses ;
+
+M: hashtable quot-uses [ >alist ] dip seq-uses ;
+
+M: callable quot-uses seq-uses ;
+
+M: wrapper quot-uses [ wrapped>> ] dip quot-uses ;
+
+M: callable uses ( quot -- assoc )
+    H{ } clone [ quot-uses ] keep keys ;
+
+M: word uses def>> uses ;
+
+M: link uses { $subsection $link $see-also } article-links ;
+
+M: pathname uses string>> source-file top-level-form>> uses ;
+
+GENERIC: crossref-def ( defspec -- )
+
+M: object crossref-def
+    dup uses crossref get add-vertex ;
+
+M: word crossref-def
+    [ call-next-method ] [ subwords [ crossref-def ] each ] bi ;
+
+: build-crossref ( -- crossref )
+    "Computing usage index... " write flush yield
+    H{ } clone crossref [
+        all-words
+        source-files get keys [ <pathname> ] map
+        [ [ crossref-def ] each ] bi@
+        crossref get
+    ] with-variable
+    "done" print flush ;
+
+: get-crossref ( -- crossref )
+    crossref global [ drop build-crossref ] cache ;
+
+GENERIC: irrelevant? ( defspec -- ? )
+
+M: object irrelevant? drop f ;
+
+M: default-method irrelevant? drop t ;
+
+M: engine-word irrelevant? drop t ;
+
+PRIVATE>
+
+: usage ( defspec -- seq ) get-crossref at keys ;
+
+GENERIC: smart-usage ( defspec -- seq )
+
+M: object smart-usage usage [ irrelevant? not ] filter ;
+
+M: method-body smart-usage "method-generic" word-prop smart-usage ;
+
+M: f smart-usage drop \ f smart-usage ;
+
 : synopsis-alist ( definitions -- alist )
     [ [ synopsis ] keep ] { } map>assoc ;
 
@@ -15,3 +90,34 @@ IN: tools.crossref
 
 : usage. ( word -- )
     smart-usage sorted-definitions. ;
+
+: vocab-xref ( vocab quot -- vocabs )
+    [ [ vocab-name ] [ words [ generic? not ] filter ] bi ] dip map
+    [
+        [ [ word? ] [ generic? not ] bi and ] filter [
+            dup method-body?
+            [ "method-generic" word-prop ] when
+            vocabulary>>
+        ] map
+    ] gather natural-sort remove sift ; inline
+
+: vocabs. ( seq -- )
+    [ dup >vocab-link write-object nl ] each ;
+
+: vocab-uses ( vocab -- vocabs ) [ uses ] vocab-xref ;
+
+: vocab-uses. ( vocab -- ) vocab-uses vocabs. ;
+
+: vocab-usage ( vocab -- vocabs ) [ usage ] vocab-xref ;
+
+: vocab-usage. ( vocab -- ) vocab-usage vocabs. ;
+
+<PRIVATE
+
+SINGLETON: invalidate-crossref
+
+M: invalidate-crossref definitions-changed 2drop crossref global delete-at ;
+
+[ invalidate-crossref add-definition-observer ] "tools.crossref" add-init-hook
+
+PRIVATE>
\ No newline at end of file
diff --git a/basis/tools/profiler/profiler-docs.factor b/basis/tools/profiler/profiler-docs.factor
index baecbd71c1..efd2e164a3 100644
--- a/basis/tools/profiler/profiler-docs.factor
+++ b/basis/tools/profiler/profiler-docs.factor
@@ -1,5 +1,5 @@
-USING: tools.profiler.private tools.time help.markup help.syntax
-quotations io strings words definitions ;
+USING: tools.profiler.private tools.time tools.crossref
+help.markup help.syntax quotations io strings words definitions ;
 IN: tools.profiler
 
 ARTICLE: "profiler-limitations" "Profiler limitations"
diff --git a/basis/tools/profiler/profiler.factor b/basis/tools/profiler/profiler.factor
index f4488136b2..219344db3b 100644
--- a/basis/tools/profiler/profiler.factor
+++ b/basis/tools/profiler/profiler.factor
@@ -3,7 +3,7 @@
 USING: accessors words sequences math prettyprint kernel arrays io
 io.styles namespaces assocs kernel.private strings combinators
 sorting math.parser vocabs definitions tools.profiler.private
-continuations generic compiler.units sets classes fry ;
+tools.crossref continuations generic compiler.units sets classes fry ;
 IN: tools.profiler
 
 : profile ( quot -- )
diff --git a/basis/tools/vocabs/vocabs.factor b/basis/tools/vocabs/vocabs.factor
index 66618ee23c..ba99a41eba 100644
--- a/basis/tools/vocabs/vocabs.factor
+++ b/basis/tools/vocabs/vocabs.factor
@@ -8,27 +8,6 @@ continuations compiler.errors init checksums checksums.crc32
 sets accessors generic definitions words ;
 IN: tools.vocabs
 
-: vocab-xref ( vocab quot -- vocabs )
-    [ [ vocab-name ] [ words [ generic? not ] filter ] bi ] dip map
-    [
-        [ [ word? ] [ generic? not ] bi and ] filter [
-            dup method-body?
-            [ "method-generic" word-prop ] when
-            vocabulary>>
-        ] map
-    ] gather natural-sort remove sift ; inline
-
-: vocabs. ( seq -- )
-    [ dup >vocab-link write-object nl ] each ;
-
-: vocab-uses ( vocab -- vocabs ) [ uses ] vocab-xref ;
-
-: vocab-uses. ( vocab -- ) vocab-uses vocabs. ;
-
-: vocab-usage ( vocab -- vocabs ) [ usage ] vocab-xref ;
-
-: vocab-usage. ( vocab -- ) vocab-usage vocabs. ;
-
 : vocab-tests-file ( vocab -- path )
     dup "-tests.factor" vocab-dir+ vocab-append-path dup
     [ dup exists? [ drop f ] unless ] [ drop f ] if ;
diff --git a/basis/ui/tools/browser/popups/popups.factor b/basis/ui/tools/browser/popups/popups.factor
index 91ac96e0f9..2cd90ab335 100644
--- a/basis/ui/tools/browser/popups/popups.factor
+++ b/basis/ui/tools/browser/popups/popups.factor
@@ -2,7 +2,7 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: accessors arrays assocs definitions fry help.topics kernel
 colors.constants math.rectangles models.arrow namespaces sequences
-sorting definitions.icons ui.gadgets ui.gadgets.glass
+sorting definitions.icons tools.crossref ui.gadgets ui.gadgets.glass
 ui.gadgets.labeled ui.gadgets.scrollers ui.gadgets.tables
 ui.gadgets.search-tables ui.gadgets.wrappers ui.gestures ui.operations
 ui.pens.solid ui.images ;
diff --git a/core/bootstrap/primitives.factor b/core/bootstrap/primitives.factor
index 4466bd9bfe..1258da8a4d 100644
--- a/core/bootstrap/primitives.factor
+++ b/core/bootstrap/primitives.factor
@@ -12,8 +12,6 @@ IN: bootstrap.primitives
 
 "Creating primitives and basic runtime structures..." print flush
 
-crossref off
-
 H{ } clone sub-primitives set
 
 "vocab:bootstrap/syntax.factor" parse-file
diff --git a/core/classes/tuple/tuple-tests.factor b/core/classes/tuple/tuple-tests.factor
index 4b556396e2..c180807b0c 100644
--- a/core/classes/tuple/tuple-tests.factor
+++ b/core/classes/tuple/tuple-tests.factor
@@ -110,8 +110,6 @@ TUPLE: yo-momma ;
     [ ] [ \ yo-momma forget ] unit-test
     [ ] [ \ <yo-momma> forget ] unit-test
     [ f ] [ \ yo-momma update-map get values memq? ] unit-test
-
-    [ f ] [ \ yo-momma crossref get at ] unit-test
 ] with-compilation-unit
 
 TUPLE: loc-recording ;
diff --git a/core/compiler/units/units-tests.factor b/core/compiler/units/units-tests.factor
index 0b74f3a236..da2dce128f 100644
--- a/core/compiler/units/units-tests.factor
+++ b/core/compiler/units/units-tests.factor
@@ -36,7 +36,7 @@ IN: compiler.units.tests
     enable-compiler
 ] unit-test
 
-! Notify observers even if compilation unit did nothing
+! Check that we notify observers
 SINGLETON: observer
 
 observer add-definition-observer
@@ -47,7 +47,7 @@ SYMBOL: counter
 
 M: observer definitions-changed 2drop global [ counter inc ] bind ;
 
-[ ] with-compilation-unit
+[ gensym [ ] (( -- )) define-declared ] with-compilation-unit
 
 [ 1 ] [ counter get-global ] unit-test
 
diff --git a/core/compiler/units/units.factor b/core/compiler/units/units.factor
index 02a80c4d84..c84e8fa73e 100644
--- a/core/compiler/units/units.factor
+++ b/core/compiler/units/units.factor
@@ -144,7 +144,7 @@ GENERIC: definitions-changed ( assoc obj -- )
     update-tuples
     process-forgotten-definitions
     modify-code-heap
-    updated-definitions notify-definition-observers
+    updated-definitions dup assoc-empty? [ drop ] [ notify-definition-observers ] if
     notify-error-observers ;
 
 : with-nested-compilation-unit ( quot -- )
diff --git a/core/definitions/definitions-docs.factor b/core/definitions/definitions-docs.factor
index 9d49cf62c6..b1575cc1e4 100644
--- a/core/definitions/definitions-docs.factor
+++ b/core/definitions/definitions-docs.factor
@@ -10,21 +10,11 @@ $nl
 { $subsection set-where }
 "Definitions can be removed:"
 { $subsection forget }
-"Definitions can answer a sequence of definitions they directly depend on:"
-{ $subsection uses }
 "Definitions must implement a few operations used for printing them in source form:"
 { $subsection definer }
 { $subsection definition }
 { $see-also "see" } ;
 
-ARTICLE: "definition-crossref" "Definition cross referencing"
-"A common cross-referencing system is used to track definition usages:"
-{ $subsection crossref }
-{ $subsection xref }
-{ $subsection unxref }
-{ $subsection delete-xref }
-{ $subsection usage } ;
-
 ARTICLE: "definition-checking" "Definition sanity checking"
 "When a source file is reloaded, the parser compares the previous list of definitions with the current list; any definitions which are no longer present in the file are removed by a call to " { $link forget } ". A warning message is printed if any other definitions still depend on the removed definitions."
 $nl
@@ -69,7 +59,6 @@ $nl
 }
 "For every source file loaded into the system, a list of definitions is maintained. Pathname objects implement the definition protocol, acting over the definitions their source files contain. See " { $link "source-files" } " for details."
 { $subsection "definition-protocol" }
-{ $subsection "definition-crossref" }
 { $subsection "definition-checking" }
 { $subsection "compilation-units" }
 "A parsing word to remove definitions:"
@@ -96,36 +85,3 @@ HELP: forget-all
 { $values { "definitions" "a sequence of definition specifiers" } }
 { $description "Forgets every definition in a sequence." }
 { $notes "This word must be called from inside " { $link with-compilation-unit } "." } ;
-
-HELP: uses
-{ $values { "defspec" "a definition specifier" } { "seq" "a sequence of definition specifiers" } }
-{ $description "Outputs a sequence of definitions directory called by the given definition." }
-{ $notes "The sequence might include the definition itself, if it is a recursive word." }
-{ $examples
-    "We can ask the " { $link sq } " word to produce a list of words it calls:"
-    { $unchecked-example "\ sq uses ." "{ dup * }" }
-} ;
-
-HELP: crossref
-{ $var-description "A graph whose vertices are definition specifiers and edges are usages. See " { $link "graphs" } "." } ;
-
-HELP: xref
-{ $values { "defspec" "a definition specifier" } }
-{ $description "Adds a vertex representing this definition, along with edges representing dependencies to the " { $link crossref } " graph." }
-$low-level-note ;
-
-HELP: usage
-{ $values { "defspec" "a definition specifier" } { "seq" "a sequence of definition specifiers" } }
-{ $description "Outputs a sequence of definitions that directly call the given definition." }
-{ $notes "The sequence might include the definition itself, if it is a recursive word." } ;
-
-HELP: unxref
-{ $values { "defspec" "a definition specifier" } }
-{ $description "Remove edges leaving the vertex which represents the definition from the " { $link crossref } " graph." }
-{ $notes "This word is called before a word is redefined." } ;
-
-HELP: delete-xref
-{ $values { "defspec" "a definition specifier" } }
-{ $description "Remove the vertex which represents the definition from the " { $link crossref } " graph." }
-{ $notes "This word is called before a word is forgotten." }
-{ $see-also forget } ;
diff --git a/core/definitions/definitions.factor b/core/definitions/definitions.factor
index 1a26e45e87..5dc3808362 100644
--- a/core/definitions/definitions.factor
+++ b/core/definitions/definitions.factor
@@ -1,6 +1,6 @@
 ! Copyright (C) 2006, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel sequences namespaces assocs graphs math math.order ;
+USING: kernel sequences namespaces assocs math ;
 IN: definitions
 
 MIXIN: definition
@@ -53,29 +53,3 @@ SYMBOL: forgotten-definitions
 GENERIC: definer ( defspec -- start end )
 
 GENERIC: definition ( defspec -- seq )
-
-SYMBOL: crossref
-
-GENERIC: uses ( defspec -- seq )
-
-M: object uses drop f ;
-
-: xref ( defspec -- ) dup uses crossref get add-vertex ;
-
-: usage ( defspec -- seq ) crossref get at keys ;
-
-GENERIC: irrelevant? ( defspec -- ? )
-
-M: object irrelevant? drop f ;
-
-GENERIC: smart-usage ( defspec -- seq )
-
-M: f smart-usage drop \ f smart-usage ;
-
-M: object smart-usage usage [ irrelevant? not ] filter ;
-
-: unxref ( defspec -- )
-    dup uses crossref get remove-vertex ;
-
-: delete-xref ( defspec -- )
-    dup unxref crossref get delete-at ;
diff --git a/core/generic/generic-tests.factor b/core/generic/generic-tests.factor
index 37f5cf40ae..e7ae583aa6 100755
--- a/core/generic/generic-tests.factor
+++ b/core/generic/generic-tests.factor
@@ -133,69 +133,19 @@ M: f tag-and-f 4 ;
 [ 3.4 3 ] [ 3.4 tag-and-f ] unit-test
 
 ! Issues with forget
-GENERIC: generic-forget-test-1 ( a b -- c )
+GENERIC: generic-forget-test ( a -- b )
 
-M: integer generic-forget-test-1 / ;
+M: f generic-forget-test ;
 
-[ t ] [
-    \ / usage [ word? ] filter
-    [ name>> "integer=>generic-forget-test-1" = ] any?
-] unit-test
-
-[ ] [
-    [ \ generic-forget-test-1 forget ] with-compilation-unit
-] unit-test
-
-[ f ] [
-    \ / usage [ word? ] filter
-    [ name>> "integer=>generic-forget-test-1" = ] any?
-] unit-test
-
-GENERIC: generic-forget-test-2 ( a b -- c )
-
-M: sequence generic-forget-test-2 = ;
-
-[ t ] [
-    \ = usage [ word? ] filter
-    [ name>> "sequence=>generic-forget-test-2" = ] any?
-] unit-test
-
-[ ] [
-    [ M\ sequence generic-forget-test-2 forget ] with-compilation-unit
-] unit-test
-
-[ f ] [
-    \ = usage [ word? ] filter
-    [ name>> "sequence=>generic-forget-test-2" = ] any?
-] unit-test
-
-GENERIC: generic-forget-test-3 ( a -- b )
-
-M: f generic-forget-test-3 ;
-
-[ ] [ \ f \ generic-forget-test-3 method "m" set ] unit-test
+[ ] [ \ f \ generic-forget-test method "m" set ] unit-test
 
 [ ] [ [ "m" get forget ] with-compilation-unit ] unit-test
 
-[ ] [ "IN: generic.tests M: f generic-forget-test-3 ;" eval( -- ) ] unit-test
+[ ] [ "IN: generic.tests M: f generic-forget-test ;" eval( -- ) ] unit-test
 
 [ ] [ [ "m" get forget ] with-compilation-unit ] unit-test
 
-[ f ] [ f generic-forget-test-3 ] unit-test
-
-: a-word ( -- ) ;
-
-GENERIC: a-generic ( a -- b )
-
-M: integer a-generic a-word ;
-
-[ ] [ \ integer \ a-generic method "m" set ] unit-test
-
-[ t ] [ "m" get \ a-word usage memq? ] unit-test
-
-[ ] [ "IN: generic.tests : a-generic ( -- ) ;" eval( -- ) ] unit-test
-
-[ f ] [ "m" get \ a-word usage memq? ] unit-test
+[ f ] [ f generic-forget-test ] unit-test
 
 ! erg's regression
 [ ] [
diff --git a/core/generic/generic.factor b/core/generic/generic.factor
index 7fdb339069..965be91642 100644
--- a/core/generic/generic.factor
+++ b/core/generic/generic.factor
@@ -123,8 +123,6 @@ M: method-body crossref?
 
 PREDICATE: default-method < word "default" word-prop ;
 
-M: default-method irrelevant? drop t ;
-
 : <default-method> ( generic combination -- method )
     [ drop object bootstrap-word swap <method> ] [ make-default-method ] 2bi
     [ define ] [ drop t "default" set-word-prop ] [ drop ] 2tri ;
@@ -155,9 +153,6 @@ M: method-body forget*
         [ call-next-method ] bi
     ] if ;
 
-M: method-body smart-usage
-    "method-generic" word-prop smart-usage ;
-
 M: sequence update-methods ( class seq -- )
     implementors [
         [ changed-generic ] [ remake-generic drop ] 2bi
@@ -192,6 +187,3 @@ M: generic forget*
 
 M: class forget-methods
     [ implementors ] [ [ swap method ] curry ] bi map forget-all ;
-
-: xref-generics ( -- )
-    all-words [ subwords [ xref ] each ] each ;
diff --git a/core/generic/standard/engines/tuple/tuple.factor b/core/generic/standard/engines/tuple/tuple.factor
index 7e91adfaa1..a0711af095 100644
--- a/core/generic/standard/engines/tuple/tuple.factor
+++ b/core/generic/standard/engines/tuple/tuple.factor
@@ -86,8 +86,6 @@ M: engine-word where "tuple-dispatch-generic" word-prop where ;
 
 M: engine-word crossref? "forgotten" word-prop not ;
 
-M: engine-word irrelevant? drop t ;
-
 : remember-engine ( word -- )
     generic get "engines" word-prop push ;
 
diff --git a/core/generic/standard/standard-tests.factor b/core/generic/standard/standard-tests.factor
index 420dd16991..58007f795f 100644
--- a/core/generic/standard/standard-tests.factor
+++ b/core/generic/standard/standard-tests.factor
@@ -280,27 +280,6 @@ M: growable call-next-hooker call-next-method "growable " prepend ;
     V{ } my-var [ call-next-hooker ] with-variable
 ] unit-test
 
-! Cross-referencing with generic words
-TUPLE: xref-tuple-1 ;
-TUPLE: xref-tuple-2 < xref-tuple-1 ;
-
-: (xref-test) ( obj -- ) drop ;
-
-GENERIC: xref-test ( obj -- )
-
-M: xref-tuple-1 xref-test (xref-test) ;
-M: xref-tuple-2 xref-test (xref-test) ;
-
-[ t ] [
-    \ xref-test
-    \ xref-tuple-1 \ xref-test method [ usage unique ] closure key?
-] unit-test
-
-[ t ] [
-    \ xref-test
-    \ xref-tuple-2 \ xref-test method [ usage unique ] closure key?
-] unit-test
-
 [ t ] [
     { } \ nth effective-method nip \ sequence \ nth method eq?
 ] unit-test
diff --git a/core/parser/parser.factor b/core/parser/parser.factor
index 9876818d26..7908f40cbe 100644
--- a/core/parser/parser.factor
+++ b/core/parser/parser.factor
@@ -264,7 +264,7 @@ print-use-hook [ [ ] ] initialize
 
 : finish-parsing ( lines quot -- )
     file get
-    [ record-form ]
+    [ record-top-level-form ]
     [ record-definitions ]
     [ record-checksum ]
     tri ;
diff --git a/core/source-files/source-files-docs.factor b/core/source-files/source-files-docs.factor
index 2c9e2172cc..eb1284cd25 100644
--- a/core/source-files/source-files-docs.factor
+++ b/core/source-files/source-files-docs.factor
@@ -11,9 +11,7 @@ $nl
 { $subsection source-file }
 "Words intended for the parser:"
 { $subsection record-checksum }
-{ $subsection record-form }
-{ $subsection xref-source }
-{ $subsection unxref-source }
+{ $subsection record-definitions }
 "Removing a source file from the database:"
 { $subsection forget-source }
 "Updating the database:"
@@ -42,25 +40,6 @@ HELP: record-checksum
 { $description "Records the CRC32 checksm of the source file's contents." } 
 $low-level-note ;
 
-HELP: xref-source
-{ $values { "source-file" source-file } }
-{ $description "Adds the source file to the " { $link crossref } " graph enabling words to find source files which reference them in their top level forms." }
-$low-level-note ;
-
-HELP: unxref-source
-{ $values { "source-file" source-file } }
-{ $description "Removes the source file from the " { $link crossref } " graph." }
-$low-level-note ;
-
-HELP: xref-sources
-{ $description "Adds all loaded source files to the " { $link crossref } " graph. This is done during bootstrap." }
-$low-level-note ;
-
-HELP: record-form
-{ $values { "quot" quotation } { "source-file" source-file } }
-{ $description "Records usage information for a source file's top level form." }
-$low-level-note ;
-
 HELP: reset-checksums
 { $description "Resets recorded modification times and CRC32 checksums for all loaded source files, creating a checkpoint for " { $link "tools.vocabs" } "." } ;
 
diff --git a/core/source-files/source-files.factor b/core/source-files/source-files.factor
index 6884a10d03..558018a147 100644
--- a/core/source-files/source-files.factor
+++ b/core/source-files/source-files.factor
@@ -1,4 +1,4 @@
-! Copyright (C) 2007, 2008 Slava Pestov.
+! Copyright (C) 2007, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: arrays definitions generic assocs kernel math namespaces
 sequences strings vectors words quotations io io.files
@@ -11,29 +11,16 @@ SYMBOL: source-files
 
 TUPLE: source-file
 path
+top-level-form
 checksum
-uses definitions ;
+definitions ;
+
+: record-top-level-form ( quot file -- )
+    (>>top-level-form) H{ } notify-definition-observers ;
 
 : record-checksum ( lines source-file -- )
     [ crc32 checksum-lines ] dip (>>checksum) ;
 
-: (xref-source) ( source-file -- pathname uses )
-    [ path>> <pathname> ]
-    [ uses>> [ crossref? ] filter ] bi ;
-
-: xref-source ( source-file -- )
-    (xref-source) crossref get add-vertex ;
-
-: unxref-source ( source-file -- )
-    (xref-source) crossref get remove-vertex ;
-
-: xref-sources ( -- )
-    source-files get [ nip xref-source ] assoc-each ;
-
-: record-form ( quot source-file -- )
-    [ quot-uses keys ] dip
-    [ unxref-source ] [ (>>uses) ] [ xref-source ] tri ;
-
 : record-definitions ( file -- )
     new-definitions get >>definitions drop ;
 
@@ -58,13 +45,8 @@ ERROR: invalid-source-file-path path ;
 M: pathname where string>> 1 2array ;
 
 : forget-source ( path -- )
-    [
-        source-file
-        [ unxref-source ]
-        [ definitions>> [ keys forget-all ] each ] bi
-    ]
-    [ source-files get delete-at ]
-    bi ;
+    source-files get delete-at*
+    [ definitions>> [ keys forget-all ] each ] [ drop ] if ;
 
 M: pathname forget*
     string>> forget-source ;
diff --git a/core/words/words-docs.factor b/core/words/words-docs.factor
index 4bed65374c..c1b8c0c229 100644
--- a/core/words/words-docs.factor
+++ b/core/words/words-docs.factor
@@ -290,10 +290,6 @@ HELP: define-temp
     "This word must be called from inside " { $link with-compilation-unit } "."
 } ;
 
-HELP: quot-uses
-{ $values { "quot" quotation } { "assoc" "an assoc with words as keys" } }
-{ $description "Outputs a set of words referenced by the quotation and any quotations it contains." } ;
-
 HELP: delimiter?
 { $values { "obj" object } { "?" "a boolean" } }
 { $description "Tests if an object is a delimiter word declared by " { $link POSTPONE: delimiter } "." }
diff --git a/core/words/words-tests.factor b/core/words/words-tests.factor
index 3ba5e1f693..0ecf7b65f0 100755
--- a/core/words/words-tests.factor
+++ b/core/words/words-tests.factor
@@ -63,52 +63,6 @@ FORGET: forgotten
 FORGET: another-forgotten
 : another-forgotten ( -- ) ;
 
-! I forgot remove-crossref calls!
-: fee ( -- ) ;
-: foe ( -- ) fee ;
-: fie ( -- ) foe ;
-
-[ t ] [ \ fee usage [ word? ] filter empty? ] unit-test
-[ t ] [ \ foe usage empty? ] unit-test
-[ f ] [ \ foe crossref get key? ] unit-test
-
-FORGET: foe
-
-! xref should not retain references to gensyms
-[ ] [
-    [ gensym [ * ] define ] with-compilation-unit
-] unit-test
-
-[ t ] [
-    \ * usage [ word? ] filter [ crossref? ] all?
-] unit-test
-
-DEFER: calls-a-gensym
-[ ] [
-    [
-        \ calls-a-gensym
-        gensym dup "x" set 1quotation
-        (( x -- x )) define-declared
-    ] with-compilation-unit
-] unit-test
-
-[ f ] [ "x" get crossref get at ] unit-test
-
-! more xref buggery
-[ f ] [
-    GENERIC: xyzzle ( x -- x )
-    : a ( -- ) ; \ a
-    M: integer xyzzle a ;
-    FORGET: a
-    M: object xyzzle ;
-    crossref get at
-] unit-test
-
-! regression
-GENERIC: freakish ( x -- y )
-: bar ( x -- y ) freakish ;
-M: array freakish ;
-[ t ] [ \ bar \ freakish usage member? ] unit-test
 
 DEFER: x
 [ x ] [ undefined? ] must-fail-with
@@ -122,26 +76,6 @@ DEFER: x
 [ ] [ "IN: words.tests : test-last ( -- ) ;" eval( -- ) ] unit-test
 [ "test-last" ] [ word name>> ] unit-test
 
-! regression
-SYMBOL: quot-uses-a
-SYMBOL: quot-uses-b
-
-[ ] [
-    [
-        quot-uses-a [ 2 3 + ] define
-    ] with-compilation-unit
-] unit-test
-
-[ { + } ] [ \ quot-uses-a uses ] unit-test
-
-[ ] [
-    [
-        quot-uses-b 2 [ 3 + ] curry define
-    ] with-compilation-unit
-] unit-test
-
-[ { + } ] [ \ quot-uses-b uses ] unit-test
-
 "undef-test" "words.tests" lookup [
     [ forget ] with-compilation-unit
 ] when*
@@ -191,8 +125,3 @@ SYMBOL: quot-uses-b
         keys [ "forgotten" word-prop ] any?
     ] filter
 ] unit-test
-
-[ { } ] [
-    crossref get keys
-    [ word? ] filter [ "forgotten" word-prop ] filter
-] unit-test
diff --git a/core/words/words.factor b/core/words/words.factor
index 1a2317997a..eb0599db78 100755
--- a/core/words/words.factor
+++ b/core/words/words.factor
@@ -62,33 +62,7 @@ SYMBOL: bootstrapping?
 GENERIC: crossref? ( word -- ? )
 
 M: word crossref?
-    dup "forgotten" word-prop [
-        drop f
-    ] [
-        vocabulary>> >boolean
-    ] if ;
-
-GENERIC# (quot-uses) 1 ( obj assoc -- )
-
-M: object (quot-uses) 2drop ;
-
-M: word (quot-uses) over crossref? [ conjoin ] [ 2drop ] if ;
-
-: seq-uses ( seq assoc -- ) [ (quot-uses) ] curry each ;
-
-M: array (quot-uses) seq-uses ;
-
-M: hashtable (quot-uses) [ >alist ] dip seq-uses ;
-
-M: callable (quot-uses) seq-uses ;
-
-M: wrapper (quot-uses) [ wrapped>> ] dip (quot-uses) ;
-
-: quot-uses ( quot -- assoc )
-    global [ H{ } clone [ (quot-uses) ] keep ] bind ;
-
-M: word uses ( word -- seq )
-    def>> quot-uses keys ;
+    dup "forgotten" word-prop [ drop f ] [ vocabulary>> >boolean ] if ;
 
 SYMBOL: compiled-crossref
 
@@ -132,11 +106,7 @@ GENERIC: subwords ( word -- seq )
 M: word subwords drop f ;
 
 : define ( word def -- )
-    [ ] like
-    over unxref
-    over changed-definition
-    >>def
-    dup crossref? [ dup xref ] when drop ;
+    over changed-definition [ ] like >>def drop ;
 
 : changed-effect ( word -- )
     [ dup changed-effects get set-in-unit ]
@@ -228,10 +198,9 @@ M: word set-where swap "loc" set-word-prop ;
 
 M: word forget*
     dup "forgotten" word-prop [ drop ] [
-        [ delete-xref ]
         [ [ name>> ] [ vocabulary>> vocab-words ] bi delete-at ]
         [ t "forgotten" set-word-prop ]
-        tri
+        bi
     ] if ;
 
 M: word hashcode*
@@ -239,6 +208,4 @@ M: word hashcode*
 
 M: word literalize <wrapper> ;
 
-: xref-words ( -- ) all-words [ xref ] each ;
-
 INSTANCE: word definition
\ No newline at end of file