diff --git a/ein-cell.el b/ein-cell.el
index 43267e4e..ddbc638f 100644
--- a/ein-cell.el
+++ b/ein-cell.el
@@ -362,13 +362,17 @@ A specific node can be specified using optional ARGS."
   ;; FIXME: change the appearance of the cell
   (oset cell :running running))
 
-(defmethod ein:cell-toggle-output ((cell ein:codecell))
-  "Toggle `:collapsed' slot of CELL and invalidate output ewoc nodes."
-  (oset cell :collapsed (not (oref cell :collapsed)))
+(defmethod ein:cell-set-collapsed ((cell ein:codecell) collapsed)
+  "Set `:collapsed' slot of CELL and invalidate output ewoc nodes."
+  (oset cell :collapsed collapsed)
   (apply #'ewoc-invalidate
          (oref cell :ewoc)
          (ein:cell-element-get cell :output)))
 
+(defmethod ein:cell-toggle-output ((cell ein:codecell))
+  "Toggle `:collapsed' slot of CELL and invalidate output ewoc nodes."
+  (ein:cell-set-collapsed cell (not (oref cell :collapsed))))
+
 (defun ein:cell-set-input-prompt (cell &optional number)
   (oset cell :input-prompt-number number)
   (let ((inhibit-read-only t)
diff --git a/ein-notebook.el b/ein-notebook.el
index 4ae6d501..5bacd02c 100644
--- a/ein-notebook.el
+++ b/ein-notebook.el
@@ -361,6 +361,17 @@ when the prefix argument is given."
   (ein:notebook-with-cell #'ein:codecell-p
     (ein:notebook-toggle-output ein:notebook cell)))
 
+(defun ein:notebook-set-collapsed-all (notebook collapsed)
+  (mapc (lambda (c)
+          (when (ein:codecell-p c) (ein:cell-set-collapsed c collapsed)))
+        (ein:notebook-get-cells notebook))
+  (setf (ein:$notebook-dirty notebook) t))
+
+(defun ein:notebook-set-collapsed-all-command (&optional show)
+  "Hide all cell output.  When prefix is given, show all cell output."
+  (interactive "P")
+  (ein:notebook-set-collapsed-all ein:notebook (not show)))
+
 
 ;;; Kernel related things
 
@@ -690,6 +701,7 @@ NAME is any non-empty string that does not contain '/' or '\\'."
     (define-key map "\C-c\C-r" 'ein:notebook-render)
     (define-key map "\C-c\C-c" 'ein:notebook-execute-current-cell)
     (define-key map "\C-c\C-e" 'ein:notebook-toggle-output-command)
+    (define-key map "\C-c\C-v" 'ein:notebook-set-collapsed-all-command)
     (define-key map "\C-c\C-d" 'ein:notebook-delete-cell-command)
     (define-key map "\C-c\C-k" 'ein:notebook-kill-cell-command)
     (define-key map "\C-c\M-w" 'ein:notebook-copy-cell-command)