diff --git a/collects/racket/set.rkt b/collects/racket/set.rkt
index 2676037d7f..3dc363eb81 100644
--- a/collects/racket/set.rkt
+++ b/collects/racket/set.rkt
@@ -6,6 +6,7 @@
          set-empty? set-count
          set-member? set-add set-remove
          set-union set-intersect set-subtract
+         set-subset?
          set-map set-for-each 
          (rename-out [*in-set in-set])
          for/set for/seteq for/seteqv
@@ -163,6 +164,18 @@
     (for/fold ([set set]) ([set2 (in-list sets)])
       (set-subtract set set2))]))
 
+(define (set-subset? set1 set2)
+  (unless (set? set1) (raise-type-error 'set-subset? "set" 0 set1 set2))
+  (unless (set? set2) (raise-type-error 'set-subset? "set" 1 set1 set2))
+  (let ([ht1 (set-ht set1)]
+        [ht2 (set-ht set2)])
+    (unless (and (eq? (hash-eq? ht1) (hash-eq? ht2))
+                 (eq? (hash-eqv? ht1) (hash-eqv? ht2)))
+      (raise-mismatch-error 'set-subset? "second set's equivalence predicate is not the same as the first set: "
+                            set2))
+    (for/and ([v (in-hash-keys ht2)])
+      (hash-ref ht1 v #f))))
+
 (define (set-map set proc)
   (unless (set? set) (raise-type-error 'set-map "set" 0 set proc))
   (unless (and (procedure? proc)
diff --git a/collects/scribblings/reference/sets.scrbl b/collects/scribblings/reference/sets.scrbl
index 32bcf72223..a61ff00c9f 100644
--- a/collects/scribblings/reference/sets.scrbl
+++ b/collects/scribblings/reference/sets.scrbl
@@ -52,11 +52,13 @@ to a later element takes precedence over the later element.}
 Returns @scheme[#t] if @scheme[set] has no members, @scheme[#f]
 otherwise.}
 
+
 @defproc[(set-member? [set set?] [v any/c]) boolean?]{
 
 Returns @scheme[#t] if @scheme[v] is in @scheme[set], @scheme[#f]
 otherwise.}
 
+
 @defproc[(set-add [set set?] [v any/c]) set?]{
 
 @margin-note{Like operations on immutable hash tables, ``constant
@@ -101,6 +103,15 @@ runs in time proportional to the total size of all given
 @scheme[set]s except the first one.}
 
 
+@defproc[(set-subset? [set set?] [set2 set?]) boolean?]{
+
+Returns @scheme[#t] if every member of @scheme[set2] is in
+@scheme[set], @scheme[#f] otherwise. The @scheme[set] and
+@scheme[set2] must use the same equivalence predicate
+(@scheme[equal?], @scheme[eq?], or @scheme[eqv?]).  This operation
+runs in time proportional to the size of @scheme[set2].}
+
+
 @defproc[(set-map [set set?]
                   [proc (any/c . -> . any/c)])
          (listof any/c)]{