diff --git a/extra/yaml/dbg/dbg.factor b/extra/yaml/dbg/dbg.factor
index 4e72977c2f..210aa75150 100644
--- a/extra/yaml/dbg/dbg.factor
+++ b/extra/yaml/dbg/dbg.factor
@@ -4,7 +4,7 @@ USING: accessors alien.c-types alien.data assocs classes.struct
 combinators continuations destructors io io.backend
 io.encodings.ascii io.encodings.string io.encodings.utf8
 io.launcher kernel libc locals math.parser prettyprint sequences
-yaml.ffi ;
+yaml.ffi yaml.private ;
 IN: yaml.dbg
 
 : event. ( event -- )
@@ -35,7 +35,7 @@ f :> done!
         event &yaml_event_delete event.
         event type>> YAML_STREAM_END_EVENT = done!
     ] with-destructors ] [
-      "error" throw
+      parser (libyaml-parser-error)
     ] if
   ] until
 ] [ . ] recover
diff --git a/extra/yaml/yaml-docs.factor b/extra/yaml/yaml-docs.factor
index b67e43b848..4fb4bed64b 100644
--- a/extra/yaml/yaml-docs.factor
+++ b/extra/yaml/yaml-docs.factor
@@ -2,7 +2,7 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: arrays assocs byte-arrays hash-sets hashtables
 help.markup help.syntax kernel linked-assocs math sequences sets
-strings ;
+strings yaml.ffi ;
 IN: yaml
 
 HELP: >yaml
@@ -33,6 +33,36 @@ HELP: yaml>
 }
 { $description "Deserializes the YAML formatted string into a Factor object." } ;
 
+HELP: libyaml-emitter-error
+{ $values
+    { "error" yaml_error_type_t } { "problem" string }
+}
+{ $description "yaml_emitter_emit returned with status 0. The slots of this error give more information." } ;
+
+HELP: libyaml-initialize-error
+{ $description "yaml_*_initialize returned with status 0. This usually means LibYAML failed to allocate memory." } ;
+
+HELP: libyaml-parser-error
+{ $values
+    { "error" yaml_error_type_t } { "problem" string } { "problem_offset" integer } { "problem_value" integer } { "problem_mark" yaml_mark_t } { "context" string } { "context_mark" yaml_mark_t }
+}
+{ $description "yaml_parser_parse returned with status 0. The slots of this error give more information." } ;
+
+HELP: yaml-no-document
+{ $description "The input of " { $link yaml> } " had no documents." } ;
+
+HELP: yaml-undefined-anchor
+{ $values
+    { "anchor" string } { "anchors" sequence }
+}
+{ $description "The document references an undefined anchor " { $snippet "anchor" } ". For information, the list of currently defined anchors in the document is " { $snippet "anchors" } "." } ;
+
+HELP: yaml-unexpected-event
+{ $values
+    { "actual" yaml_event_type_t } { "expected" sequence }
+}
+{ $description "LibYAML produced the unexpected event " { $snippet "actual" } ", but the list of expected events is " { $snippet "expected" } "." } ;
+
 ARTICLE: "yaml-mapping" "Mapping between Factor and YAML types"
 { $heading "Types mapping" }
 "The rules in the table below are used to convert between yaml and factor objects."
@@ -90,6 +120,25 @@ ARTICLE: "yaml-input" "Deserialization control"
   "etc."
 }
 ;
+ARTICLE: "yaml-errors" "YAML errors"
+{ $heading "libYAML's errors" }
+"LibYAML exposes error when parsing/emitting yaml. See " { $url "http://pyyaml.org/wiki/LibYAML" } ". More information is available directly in pyyaml's source code in their C interface. They are groupped in the following errors:"
+{ $list
+  { $link libyaml-parser-error }
+  { $link libyaml-emitter-error }
+  { $link libyaml-initialize-error }
+}
+{ $heading "Conversion errors" }
+"Additional errors are thrown when converting to/from factor objects:"
+{ $list
+  { $link yaml-undefined-anchor }
+  { $link yaml-no-document }
+  "Or many errors thrown by library words (eg unparseable numbers, converting unsupported objects to yaml, etc)"
+}
+{ $heading "Bugs" }
+"The following error probably means that there is a bug in the implementation: " { $link yaml-unexpected-event }
+;
+
 ARTICLE: "yaml" "YAML serialization"
 "The " { $vocab-link "yaml" } " vocabulary implements YAML serialization/deserialization."
 { $heading "Main conversion words" }
@@ -104,6 +153,7 @@ ARTICLE: "yaml" "YAML serialization"
 "yaml-mapping"
 "yaml-output"
 "yaml-input"
+"yaml-errors"
 }
 { $examples
   { $example "USING: prettyprint yaml ;"
diff --git a/extra/yaml/yaml-tests.factor b/extra/yaml/yaml-tests.factor
index 8cb60bd304..64dd88ed6c 100644
--- a/extra/yaml/yaml-tests.factor
+++ b/extra/yaml/yaml-tests.factor
@@ -111,9 +111,6 @@ CONSTANT: fancy-anchors-obj {
 ${ fancy-anchors-obj } [ $ fancy-anchors yaml> ] unit-test
 ${ fancy-anchors-obj } [ $ fancy-anchors-obj >yaml yaml> ] unit-test
 
-! Missing anchors
-[ "*foo" yaml> ] [ "No previous anchor" = ] must-fail-with
-
 ! Simple Recursive output
 : simple-recursive-list ( -- obj )
   { f } clone [ 0 over set-nth ] keep ;
@@ -561,4 +558,8 @@ ${ construct-value-obj } [ $ construct-value-str yaml-docs> ] unit-test
 ${ construct-value-obj } [ $ construct-value-obj >yaml-docs yaml-docs> ] unit-test
 
 ! !!!!!!!!!!!!!!!
-! *.detect
+! errors
+
+[ "- foo\n:)" yaml> ] [ libyaml-parser-error? ] must-fail-with
+[ "- &foo 1\n- *baz\n" yaml> ] [ yaml-undefined-anchor? ] must-fail-with
+[ "" yaml> ] [ yaml-no-document? ] must-fail-with
diff --git a/extra/yaml/yaml.factor b/extra/yaml/yaml.factor
index 92fc1c1555..8365305bfe 100644
--- a/extra/yaml/yaml.factor
+++ b/extra/yaml/yaml.factor
@@ -2,16 +2,43 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: accessors alien.data arrays assocs byte-arrays
 classes.struct combinators combinators.extras
-combinators.short-circuit destructors fry hashtables
-hashtables.identity io.encodings.string io.encodings.utf8 kernel
-libc linked-assocs locals make math math.parser namespaces
-sequences sets strings yaml.conversion yaml.ffi ;
+combinators.short-circuit destructors fry generalizations
+hashtables hashtables.identity io.encodings.string
+io.encodings.utf8 kernel libc linked-assocs locals make math
+math.parser namespaces sequences sets strings yaml.conversion
+yaml.ffi ;
 FROM: sets => set ;
 IN: yaml
 
+ERROR: libyaml-parser-error
+    error problem problem_offset
+    problem_value problem_mark context context_mark ;
+ERROR: libyaml-initialize-error ;
+ERROR: libyaml-emitter-error error problem ;
+
+ERROR: yaml-undefined-anchor anchor anchors ;
+ERROR: yaml-unexpected-event actual expected ;
+ERROR: yaml-no-document ;
+
 <PRIVATE
 
-: yaml-assert-ok ( ? -- ) [ "yaml error" throw ] unless ;
+: yaml-initialize-assert-ok ( ? -- ) [ libyaml-initialize-error ] unless ;
+: (libyaml-parser-error) ( parser -- )
+    {
+        [ error>> ] [ problem>> ] [ problem_offset>> ] [ problem_value>> ]
+        [ problem_mark>> ] [ context>> ] [ context_mark>> ]
+    } cleave [ clone ] 7 napply libyaml-parser-error ;
+: (libyaml-emitter-error) ( emitter -- )
+    [ error>> ] [ problem>> ] bi [ clone ] bi@ libyaml-emitter-error ;
+: yaml-parser-assert-ok ( ? parser -- )
+    swap [ drop ] [ (libyaml-parser-error) ] if ;
+: yaml-emitter-assert-ok ( ? emitter -- )
+    swap [ drop ] [ (libyaml-emitter-error) ] if ;
+
+: yaml_parser_parse_asserted ( parser event -- )
+    [ yaml_parser_parse ] [ drop yaml-parser-assert-ok ] 2bi ;
+: yaml_emitter_emit_asserted ( emitter event -- )
+    [ yaml_emitter_emit ] [ drop yaml-emitter-assert-ok ] 2bi ;
 
 TUPLE: yaml-alias anchor ;
 C: <yaml-alias> yaml-alias
@@ -19,8 +46,8 @@ SYMBOL: anchors
 : ?register-anchor ( obj event -- obj )
     dupd anchor>> [ anchors get set-at ] [ drop ] if* ;
 : assert-anchor-exists ( anchor -- )
-    anchors get at* nip
-    [ "No previous anchor" throw ] unless ;
+    anchors get 2dup at* nip
+    [ 2drop ] [ yaml-undefined-anchor ] if ;
 
 : deref-anchor ( event -- obj )
     data>> alias>> anchor>>
@@ -47,7 +74,6 @@ TUPLE: factor_yaml_event_t type data start_mark end_mark ;
     [ data>> ] [ type>> ] bi {
         { YAML_SEQUENCE_START_EVENT [ sequence_start>> deep-copy-seq f ] }
         { YAML_MAPPING_START_EVENT [ mapping_start>> deep-copy-map f swap ] }
-        [ throw ]
     } case factor_event_data boa ;
 : deep-copy-event ( event -- event' )
     { [ type>> ] [ deep-copy-data ] [ start_mark>> ] [ end_mark>> ] } cleave
@@ -62,7 +88,7 @@ TUPLE: factor_yaml_event_t type data start_mark end_mark ;
 
 ! Must not reuse the event struct before with-destructors scope ends
 : next-event ( parser event -- event )
-    [ yaml_parser_parse yaml-assert-ok ] [ &yaml_event_delete ] bi ;
+    [ yaml_parser_parse_asserted ] [ &yaml_event_delete ] bi ;
 
 DEFER: parse-sequence
 DEFER: parse-mapping
@@ -76,7 +102,6 @@ DEFER: parse-mapping
     dup type>> {
         { YAML_SEQUENCE_START_EVENT [ (parse-sequence) ] }
         { YAML_MAPPING_START_EVENT [ (parse-mapping) ] }
-        [ throw ]
     } case ;
 
 :: next-value ( parser event -- obj )
@@ -122,8 +147,8 @@ DEFER: parse-mapping
 
 : expect-event ( parser event type -- )
     [
-        [ next-event type>> ] dip =
-        [ "wrong event" throw ] unless
+        [ next-event type>> ] dip 2dup =
+        [ 2drop ] [ 1array yaml-unexpected-event ] if
     ] with-destructors ;
 
 GENERIC: (deref-aliases) ( anchors obj -- obj' )
@@ -152,7 +177,7 @@ M: assoc (deref-aliases)
         parser event next-event type>> {
             { YAML_DOCUMENT_START_EVENT [ t ] }
             { YAML_STREAM_END_EVENT [ f ] }
-            [ "wrong event" throw ]
+            [ { YAML_DOCUMENT_START_EVENT YAML_STREAM_END_EVENT } yaml-unexpected-event ]
         } case
     ] with-destructors
     [
@@ -163,7 +188,7 @@ M: assoc (deref-aliases)
 ! registers destructors (use with with-destructors)
 :: init-parser ( str -- parser event )
     yaml_parser_t (malloc-struct) &free :> parser
-    parser yaml_parser_initialize yaml-assert-ok
+    parser yaml_parser_initialize yaml-initialize-assert-ok
     parser &yaml_parser_delete drop
 
     str utf8 encode
@@ -179,7 +204,7 @@ PRIVATE>
     [
         init-parser
         [ YAML_STREAM_START_EVENT expect-event ]
-        [ ?parse-yaml-doc [ "No Document" throw ] unless ] 2bi
+        [ ?parse-yaml-doc [ yaml-no-document ] unless ] 2bi
     ] with-destructors ;
 
 : yaml-docs> ( str -- arr )
@@ -262,25 +287,25 @@ GENERIC: emit-value ( emitter event anchor obj -- )
     event anchor
     obj [ yaml-tag ] [ represent-scalar ] bi
     -1 f f YAML_ANY_SCALAR_STYLE
-    yaml_scalar_event_initialize yaml-assert-ok
-    emitter event yaml_emitter_emit yaml-assert-ok ;
+    yaml_scalar_event_initialize yaml-initialize-assert-ok
+    emitter event yaml_emitter_emit_asserted ;
 
 M: object emit-value ( emitter event anchor obj -- ) emit-scalar ;
 
 M: yaml-anchor emit-value ( emitter event unused obj -- )
     nip [ anchor>> ] [ obj>> ] bi emit-value ;
 M:: yaml-alias emit-value ( emitter event unused obj -- )
-    event obj anchor>> yaml_alias_event_initialize yaml-assert-ok
-    emitter event yaml_emitter_emit yaml-assert-ok ;
+    event obj anchor>> yaml_alias_event_initialize yaml-initialize-assert-ok
+    emitter event yaml_emitter_emit_asserted ;
 
 :: emit-sequence-start ( emitter event anchor tag -- )
     event anchor tag f YAML_ANY_SEQUENCE_STYLE
-    yaml_sequence_start_event_initialize yaml-assert-ok
-    emitter event yaml_emitter_emit yaml-assert-ok ;
+    yaml_sequence_start_event_initialize yaml-initialize-assert-ok
+    emitter event yaml_emitter_emit_asserted ;
 
 : emit-sequence-end ( emitter event -- )
-    dup yaml_sequence_end_event_initialize yaml-assert-ok
-    yaml_emitter_emit yaml-assert-ok ;
+    dup yaml_sequence_end_event_initialize yaml-initialize-assert-ok
+    yaml_emitter_emit_asserted ;
 
 : emit-sequence-body ( emitter event seq -- )
     [ emit-object ] with with each ;
@@ -305,12 +330,12 @@ M: linked-assoc emit-value ( emitter event anchor assoc -- )
 
 :: emit-assoc-start ( emitter event anchor tag -- )
     event anchor tag f YAML_ANY_MAPPING_STYLE
-    yaml_mapping_start_event_initialize yaml-assert-ok
-    emitter event yaml_emitter_emit yaml-assert-ok ;
+    yaml_mapping_start_event_initialize yaml-initialize-assert-ok
+    emitter event yaml_emitter_emit_asserted ;
 
 : emit-assoc-end ( emitter event -- )
-    dup yaml_mapping_end_event_initialize yaml-assert-ok
-    yaml_emitter_emit yaml-assert-ok ;
+    dup yaml_mapping_end_event_initialize yaml-initialize-assert-ok
+    yaml_emitter_emit_asserted ;
 
 M: assoc emit-value ( emitter event anchor assoc -- )
     [ drop YAML_MAP_TAG emit-assoc-start ]
@@ -324,7 +349,7 @@ M: set emit-value ( emitter event anchor set -- )
 ! registers destructors (use with with-destructors)
 :: init-emitter ( -- emitter event )
     yaml_emitter_t (malloc-struct) &free :> emitter
-    emitter yaml_emitter_initialize yaml-assert-ok
+    emitter yaml_emitter_initialize yaml-initialize-assert-ok
     emitter &yaml_emitter_delete drop
 
     BV{ } clone :> output
@@ -334,26 +359,26 @@ M: set emit-value ( emitter event anchor set -- )
     yaml_event_t (malloc-struct) &free :> event
 
     event YAML_UTF8_ENCODING
-    yaml_stream_start_event_initialize yaml-assert-ok
+    yaml_stream_start_event_initialize yaml-initialize-assert-ok
 
-    emitter event yaml_emitter_emit yaml-assert-ok
+    emitter event yaml_emitter_emit_asserted
     emitter event ;
 
 :: emit-doc ( emitter event obj -- )
-    event f f f f yaml_document_start_event_initialize yaml-assert-ok
-    emitter event yaml_emitter_emit yaml-assert-ok
+    event f f f f yaml_document_start_event_initialize yaml-initialize-assert-ok
+    emitter event yaml_emitter_emit_asserted
 
     emitter event obj emit-object
 
-    event f yaml_document_end_event_initialize yaml-assert-ok
-    emitter event yaml_emitter_emit yaml-assert-ok ;
+    event f yaml_document_end_event_initialize yaml-initialize-assert-ok
+    emitter event yaml_emitter_emit_asserted ;
 
 ! registers destructors (use with with-destructors)
 :: flush-emitter ( emitter event -- str )
-    event yaml_stream_end_event_initialize yaml-assert-ok
-    emitter event yaml_emitter_emit yaml-assert-ok
+    event yaml_stream_end_event_initialize yaml-initialize-assert-ok
+    emitter event yaml_emitter_emit_asserted
 
-    emitter yaml_emitter_flush yaml-assert-ok
+    emitter [ yaml_emitter_flush ] [ yaml-emitter-assert-ok ] bi
     yaml-write-buffer get utf8 decode ;
 
 PRIVATE>