diff --git a/collects/slideshow/cmdline.rkt b/collects/slideshow/cmdline.rkt
index aa4a1dd34b..03186124e7 100644
--- a/collects/slideshow/cmdline.rkt
+++ b/collects/slideshow/cmdline.rkt
@@ -44,6 +44,7 @@
     (define print-target #f)
     (define smoothing? #t)
     (define screen-number 0)
+    (define half-screen? #f)
     
     (define init-page 0)
 
@@ -121,6 +122,10 @@
          (set! use-prefetch-in-preview? #t))
         (("--keep-titlebar") "give the slide window a title bar and resize border"
          (set! keep-titlebar? #t))
+        (("--half-screen") "display slides on right half of the screen"
+         (set! half-screen? #t)
+         (set! keep-titlebar? #t)
+         (set! actual-screen-w (/ actual-screen-w 2)))
         (("--comment") "display commentary in window"
          (set! commentary? #t))
         (("--comment-on-slide") "display commentary on slide"
diff --git a/collects/slideshow/sig.rkt b/collects/slideshow/sig.rkt
index d3747e11b5..5716100206 100644
--- a/collects/slideshow/sig.rkt
+++ b/collects/slideshow/sig.rkt
@@ -99,6 +99,7 @@
      trust-me?
      quad-view?
      keep-titlebar?
+     half-screen? 
      two-frames?
      use-prefetch?
      use-prefetch-in-preview?
diff --git a/collects/slideshow/viewer.rkt b/collects/slideshow/viewer.rkt
index 2392c2ce3c..5f83e29f71 100644
--- a/collects/slideshow/viewer.rkt
+++ b/collects/slideshow/viewer.rkt
@@ -414,6 +414,9 @@
 	    (values 0 0)
 	    (get-display-left-top-inset #:monitor config:screen-number)))
 
+      (when config:half-screen?
+        (set! screen-left-inset (- screen-left-inset config:actual-screen-w)))
+
       (define fullscreen?
         (and (not config:keep-titlebar?)
              (let-values ([(w h) (get-display-size #t #:monitor config:screen-number)])