diff --git a/collects/2htdp/private/clauses-spec-and-process.rkt b/collects/2htdp/private/clauses-spec-and-process.rkt
index df541abd53..a274e0ac42 100644
--- a/collects/2htdp/private/clauses-spec-and-process.rkt
+++ b/collects/2htdp/private/clauses-spec-and-process.rkt
@@ -36,12 +36,12 @@
          (syntax-case p ()
            [(_ x) #`(proc> #,tag (f2h x) arity)]
            [_ (err tag p)])))]
-    [(_ arity except extra)
+    [(_ arity except extra ...)
      (lambda (tag)
        (lambda (p)
          (syntax-case p ()
            [(_ x) #`(proc> #,tag (f2h x) arity)]
-           extra
+           extra ...
            [_ (err tag p)])))]))
 
 (define (err spec p . xtras)
diff --git a/collects/2htdp/private/timer.rkt b/collects/2htdp/private/timer.rkt
index 3c18ee8dfc..5507672ef9 100644
--- a/collects/2htdp/private/timer.rkt
+++ b/collects/2htdp/private/timer.rkt
@@ -8,7 +8,7 @@
 ;; tick field, which the super-class uses to define the callback.
 
 
-(require "check-aux.rkt")
+(require "check-aux.rkt" "stop.rkt")
 
 (provide clock-mixin start-stop<%>)
 
@@ -19,13 +19,21 @@
     (inherit ptock)
     (init-field [on-tick #f])
     (field [rate  0]
+           [limit #f]
            [tick  void]
-           [timer (new timer% [notify-callback (lambda () (ptock))])])
-    (cond
-      [(cons? on-tick)      (set! rate (second on-tick))
-                            (set! tick (first on-tick))]
-      [(procedure? on-tick) (set! rate RATE)
-                            (set! tick on-tick)]
+           [tick# 0]
+           [timer (new timer% [notify-callback (lambda () (set! tick# (+ tick# 1)) (ptock))])])
+    (match on-tick
+      [`(,handler ,r ,l) 
+       (set! limit l)
+       (set! rate r)
+       (set! tick (first on-tick))]
+      [`(,handler ,r) 
+       (set! rate r)
+       (set! tick handler)]
+      [(? procedure? handler)
+       (set! rate RATE)
+       (set! tick handler)]
       [else (void)])
     (define/override (start!)
       (unless (<= rate 0)
@@ -35,7 +43,9 @@
       (send timer stop)
       (super stop! w))
     (define/override (pptock w)
-      (tick w))
+      (if (and limit (> tick# limit))
+          (make-stop-the-world w)
+          (tick w)))
     (define/override (name-of-tick-handler)
       (object-name tick))
     (super-new)))
diff --git a/collects/2htdp/private/universe.rkt b/collects/2htdp/private/universe.rkt
index 65bb27e6f0..37cd530f5f 100644
--- a/collects/2htdp/private/universe.rkt
+++ b/collects/2htdp/private/universe.rkt
@@ -8,6 +8,7 @@
          "timer.rkt"    
          "last.rkt"
          "clauses-spec-aux.rkt"
+         "stop.rkt"
          htdp/error
          (only-in mzlib/etc evcase)
          string-constants)
@@ -85,8 +86,11 @@
             (with-handlers ([exn? handler])
               (define ___  (begin 'dummy body ...))
 	      (define n (if (object-name name) (object-name name) name))
-              (define-values (u mails bad) 
-                (bundle> n (name (send universe get) a ...)))
+              (define nxt (name (send universe get) a ...))
+              (define-values (u mails bad)
+                (if (stop-the-world? nxt)
+                    (error 'stop! "the universe stopped: ~e" (stop-the-world-world nxt))
+                    (bundle> n nxt)))
               (send universe set (format "value returned from ~a" 'name) u)
               (unless (boolean? to-string) (send gui add (to-string u)))
               (broadcast mails)
diff --git a/collects/2htdp/tests/mouse-evt.rkt b/collects/2htdp/tests/mouse-evt.rkt
index 8e3740dc86..12df8905dc 100644
--- a/collects/2htdp/tests/mouse-evt.rkt
+++ b/collects/2htdp/tests/mouse-evt.rkt
@@ -1,4 +1,4 @@
-#lang scheme
+#lang racket
 
 (require 2htdp/universe)
 (require htdp/image)
@@ -17,25 +17,26 @@
   (cond
     [(equal? a-world world1)
      (place-image (text "move mouse in to canvas" 11 'red) 10 10
-       (place-image sq (posn-x a-world) (posn-y a-world) mt))]
+                  (place-image sq (posn-x a-world) (posn-y a-world) mt))]
     [(equal? a-world world-in)
      (place-image (text "move mouse out of canvas" 11 'red) 10 10
-       (place-image sq (posn-x a-world) (posn-y a-world) mt))]
+                  (place-image sq (posn-x a-world) (posn-y a-world) mt))]
     [else
-      (place-image sq (posn-x a-world) (posn-y a-world) mt)]))
+     (place-image sq (posn-x a-world) (posn-y a-world) mt)]))
 
 (check-expect (mouse-handler 'w 100 100 "leave") (make-posn 250 250))
 
 (define (mouse-handler w x y me)
- (cond
-   [(string=? "button-down" me) w]
-   [(string=? "button-up" me) w]
-   [(string=? "drag" me) w]
-   [(string=? "move" me) w]
-   [(string=? "enter" me) world-in]
-   [(string=? "leave" me) world-out]))
+  (cond
+    [(string=? "button-down" me) w]
+    [(string=? "button-up" me) w]
+    [(string=? "drag" me) w]
+    [(string=? "move" me) w]
+    [(string=? "enter" me) world-in]
+    [(string=? "leave" me) world-out]))
 
-(define (out? w) (equal? world-out w))
+(define (out? w)
+  (equal? world-out w))
 
 (define (main w)
   (big-bang world1 (on-draw draw) (stop-when out?) (on-mouse mouse-handler)))
diff --git a/collects/2htdp/tests/on-tick-universe-with-limit.rkt b/collects/2htdp/tests/on-tick-universe-with-limit.rkt
new file mode 100644
index 0000000000..affce61ded
--- /dev/null
+++ b/collects/2htdp/tests/on-tick-universe-with-limit.rkt
@@ -0,0 +1,13 @@
+#lang racket 
+
+(require 2htdp/universe 2htdp/image)
+
+(with-handlers ((exn? (lambda (w) 
+                        (unless (string=? "stop!: the universe stopped: 3" (exn-message w))
+                          (raise w)))))
+  (universe 0 
+            (on-tick (lambda (w) (make-bundle (add1 w) '() '())) 1/28 3)
+            (on-msg void)
+            (on-new cons))
+  (error "the universe didn't stop properly"))
+      
\ No newline at end of file
diff --git a/collects/2htdp/tests/on-tick-with-limit.rkt b/collects/2htdp/tests/on-tick-with-limit.rkt
new file mode 100644
index 0000000000..fc240ebce2
--- /dev/null
+++ b/collects/2htdp/tests/on-tick-with-limit.rkt
@@ -0,0 +1,8 @@
+#lang racket 
+
+(require 2htdp/universe 2htdp/image)
+
+(big-bang 0 
+          (on-tick add1 1/28 3)
+          (to-draw (lambda (w) (circle (- 100 w) 'solid 'red))))
+      
\ No newline at end of file
diff --git a/collects/2htdp/tests/xtest b/collects/2htdp/tests/xtest
index 90f598586c..ebe53ef107 100755
--- a/collects/2htdp/tests/xtest
+++ b/collects/2htdp/tests/xtest
@@ -30,3 +30,5 @@ run world0-stops.rkt
 run record.rkt
 run record-stop-when.rkt
 run stop-when-crash.rkt
+run on-tick-universe-with-limit.rkt
+run on-tick-with-limit.rkt
diff --git a/collects/2htdp/universe.rkt b/collects/2htdp/universe.rkt
index c28e444a8b..00f894e64c 100644
--- a/collects/2htdp/universe.rkt
+++ b/collects/2htdp/universe.rkt
@@ -56,7 +56,14 @@
              #'(list 
                 (proc> 'on-tick (f2h f) 1)
                 (num> 'on-tick rate (lambda (x) (and (real? x) (positive? x)))
-                      "positive number" "rate"))])]
+                      "positive number" "rate"))]
+            [(_ f rate limit)
+             #'(list 
+                (proc> 'on-tick (f2h f) 1)
+                (num> 'on-tick rate (lambda (x) (and (real? x) (positive? x)))
+                      "positive number" "rate")
+                (num> 'on-tick limit (lambda (x) (and (integer? x) (positive? x)))
+                      "positive integer" "limit"))])]
   ;; -- state specifies whether to display the current state 
   [state DEFAULT #'#f (expr-with-check any> "expected a boolean or a string")]
   ;; Any -> Boolean 
diff --git a/collects/teachpack/2htdp/scribblings/universe.scrbl b/collects/teachpack/2htdp/scribblings/universe.scrbl
index f8fbd2a8f9..c0050dcc1e 100644
--- a/collects/teachpack/2htdp/scribblings/universe.scrbl
+++ b/collects/teachpack/2htdp/scribblings/universe.scrbl
@@ -167,6 +167,7 @@ The design of a world program demands that you come up with a data
               ([clause
 		 (on-tick tick-expr)
 		 (on-tick tick-expr rate-expr)
+		 (on-tick tick-expr rate-expr limit-expr)
 		 (on-key key-expr)
 		 (on-release release-expr)
 		 (on-mouse mouse-expr)
@@ -251,6 +252,18 @@ tells DrRacket to call the @racket[tick-expr] function on the current
 world every time the clock ticks. The result of the call becomes the
 current world. The clock ticks every @racket[rate-expr] seconds.}}
 
+@item{
+@defform/none[#:literals(on-tick)
+              (on-tick tick-expr rate-expr limit-expr)
+              #:contracts
+              ([tick-expr (-> (unsyntax @tech{WorldState}) (unsyntax @tech{WorldState}))]
+               [rate-expr (and/c real? positive?)]
+	       [limit-expr (and/c integer? positive?)])]{
+tells DrRacket to call the @racket[tick-expr] function on the current
+world every time the clock ticks. The result of the call becomes the
+current world. The clock ticks every @racket[rate-expr] seconds. 
+The world ends when the clock has ticked more than @scheme[limit-expr] times.}}
+
 @item{A @tech{KeyEvent} represents key board events. 
 
 @deftech{KeyEvent} : @racket[string?]
@@ -714,6 +727,14 @@ As mentioned, all event handlers may return @tech{WorldState}s or
                [rate-expr (and/c real? positive?)])]{
 }
 
+@defform/none[#:literals (on-tick)
+              (on-tick tick-expr rate-expr)
+              #:contracts
+              ([tick-expr (-> (unsyntax @tech{WorldState}) (or/c (unsyntax @tech{WorldState}) package?))]
+               [rate-expr (and/c real? positive?)]
+	       [limit-expr (and/c integer? positive?)])]{
+}
+
 @defform/none[#:literals (on-key)
               (on-key key-expr)
               #:contracts
@@ -955,6 +976,7 @@ The @tech{server} itself is created with a description that includes the
 		 (on-msg msg-expr)
 		 (on-tick tick-expr)
 		 (on-tick tick-expr rate-expr)
+		 (on-tick tick-expr rate-expr limit-expr)
 		 (on-disconnect dis-expr)
 		 (state boolean-expr)
 		 (to-string render-expr)
@@ -1034,7 +1056,18 @@ optional handlers:
                [rate-expr (and/c real? positive?)])]{ 
  tells DrRacket to apply @racket[tick-expr] as above; the clock ticks
  every  @racket[rate-expr] seconds.}
-}
+
+@defform/none[#:literals (on-tick)
+              (on-tick tick-expr rate-expr)
+              #:contracts
+              ([tick-expr (-> (unsyntax @tech{UniverseState}) bundle?)]
+               [rate-expr (and/c real? positive?)]
+               [limit-expr (and/c integer? positive?)])]{ 
+ tells DrRacket to apply @racket[tick-expr] as above; the clock ticks
+ every  @racket[rate-expr] seconds. The universe stops when the clock has
+ ticked more than @scheme[limit-expr] times.}
+ }
+
 
 @item{
  @defform[(on-disconnect dis-expr)