diff --git a/pkgs/racket-test-core/tests/racket/string.rktl b/pkgs/racket-test-core/tests/racket/string.rktl
index 07cd8c4b9a..2eeabedf14 100644
--- a/pkgs/racket-test-core/tests/racket/string.rktl
+++ b/pkgs/racket-test-core/tests/racket/string.rktl
@@ -510,4 +510,17 @@
   (test #f string-suffix? "racket" "r")
   (test #f string-suffix? "racket" "kat"))
 
+;; ---------- string-contains? ----------
+
+(let ()
+  (test #t string-contains? "racket" "racket")
+  (test #t string-contains? "racket" "cket")
+  (test #t string-contains? "racket" "acke")
+  (test #t string-contains? "racket" "t")
+  (test #t string-contains? "racket" "")
+  (test #f string-contains? "racket" "b")
+  (test #f string-contains? "racket" "R")
+  (test #f string-contains? "racket" "kc")
+  (test #f string-contains? "racket" "racketr"))
+
 (report-errs)
diff --git a/racket/collects/racket/string.rkt b/racket/collects/racket/string.rkt
index dfeb5f82bf..b42b68b627 100644
--- a/racket/collects/racket/string.rkt
+++ b/racket/collects/racket/string.rkt
@@ -8,7 +8,8 @@
          string-replace
          non-empty-string?
          string-prefix?
-         string-suffix?)
+         string-suffix?
+         string-contains?)
 
 (define string-append*
   (case-lambda [(strs) (apply string-append strs)] ; optimize common cases
@@ -159,3 +160,17 @@
          (or (= i l2)
              (and (char=? (string-ref str i+o) (string-ref suffix i))
                   (loop (add1 i+o) (add1 i)))))))
+
+(define (string-contains? str sub)
+  (define L1 (string-length str))
+  (define L2 (string-length sub))
+  (define d (- L1 L2))
+  (or (zero? L2)
+      (let loop ([start 0])
+        (and (<= start d)
+             (or (let loop2 ([offset 0])
+                   (or (= offset L2)
+                       (and (char=? (string-ref str (+ start offset))
+                                    (string-ref sub offset))
+                            (loop2 (add1 offset)))))
+                 (loop (add1 start)))))))