For the most part you will likely set up your Mac’s display in its default landscape orientation; however, there may be times when you might find it could be more convenient to have your Mac oriented such that its display is at a 90 or 180 degree orientation.
For instance, flipping an external monitor on its side will allow you to better view letters and text documents, especially when handled in full-screen mode. This orientation may be relatively easy for external monitors, but can also be done for built-in ones if you can imagine mounting an iMac on its side, or opening up a MacBook and propping it on end.
OS X supports rotating any attached display on your Mac; however, the controls for this are hidden by default. To reveal them, you will need to open the System Preferences and then hold the Option-Command keys together when opening the Displays system preferences pane. However, this will not work if you already had the Displays pane open and merely returned to the main system preferences view to re-open it with these keys held down. Instead, you need to fully close the system preferences, and then re-open them before you can open the Displays preferences in this manner.

This menu will appear when you open the Displays system preferences while holding the Option and Command keys on your keyboard.
Once opened, you will have a small Rotation menu that will allow you to select 0, 90, 180, and 270 degrees of rotation for your display. Doing so will rotate your display, but then give a small message that will allow you to revert the rotation by pressing Enter, or choose the option to confirm the rotation.
I found an old video I’d created to demonstrate this capability way back in Snow Leopard! It required pressing command-option BEFORE opening the Display System Pref.
I wonder if there is a list of ‘hidden’ features that “command-option” can reveal?! It’s sometimes amazing at what Apple includes that will probably be very seldom used, and then removes things that so many of us use, like a simply, consistent interface with iTunes! [rolleyes]
Following your instructions exactly, the Rotation control does not appear.
iMac 27″ Later 2012, Mac OS X 10.10.5
The key, as it was many OSes ago, is to have the command and option keys down when you FIRST select the Displays prefs.. If you selected Displays before attempting this change, you will have to Quit System Prefs and THEN open it again and THEN press command-option. Sorry, that’s just the way it works. Why? I have no idea! 8+O
It’s a good thing I don’t need this feature because it does not work on my 27″ iMac running OS X 10.9 Mavericks, even though I have the iMac mounted on an extension arm that provides for such rotation. Of course, on a large screen like mine such rotation is far less likely to be needed, but I am surprised that it’s not even possible.
Well, it does work on Mavericks on my ancient 2009 15″ MBP which is arguably less likely to need it.
Any chance that you didn’t press command-option the first time you opened the Displays panel after launching System Preferences? Just going back to the list of panels and opening Displays again will NOT work.
I’ve got a couple of screens that are *designed* with mounts that swivel, and System Prefs recognises this (10.9) – I never need to hold down any keys to get the Rotation control. Was the same on my previous computer running 10.6.
I tried it repeatedly and without success with my Mavericks iMac system.
Yes, I did press command-option the first time.
I just figured this is another case where “OS X” means “latest version of OS X”.
Did you also Quit System Prefs between attempts? In my experience, even in Snow Leopard, one must start with a newly opened System Prefs. 😉 I think it is a protection system Apple built in to prevent inordinate amounts of tom-foolery around April 1. LOL!
Yes, I did.
I also thought my key remapper app and remapping of the modifier keys might be a problem (I use an old IBM keyboard). So I killed that app, reset the modifier keys to default and dug out the original iMac keyboard. It didn’t make any difference.
Maybe my copy of OS X is damaged. It’s over 1.5 years old and has probably lost some of its original level of integrity. I notice hiccups occurring a little more often as time has gone by. Today I hit the “go to sleep” key sequence and the OS powered down. Nice!
As an aside, I’m not impressed with Apple’s method of hiding otherwise useful features by requiring some mysterious sequence of key strokes and actions. They could have just put it in a sub-menu accessed via an “advanced” button. This keeping the user safe from using their own computer is B.S.
I really regret switching from Windows to OS X. Windows is far from perfect but the whole Apple do it our way or the highway philosophy leaves me cold.
I totally agree with you. While I understand the need to round up certain unusual settings that could confuse novice users and label them as “advanced settings”. I understand discouraging most users from altering them.
But more advanced users should be able to discover those settings in a relatively straightforward way.
The need to use arcane, undocumented keystrokes at very specific and un-intuitive times is simply unforgivable. I bet many of us wouldn’t even know that OS X is able to rotate the display if we had not read it in MacIssues. It’s hard to even google something when you don’t even know it exists!
Honestly, this dumbing down of the interface and display of contempt for the power users may be what eventually drives me away from the Mac.