Here's how to make your MacBook Pro retina into a brick if someone steals it, and how to hopefully get it back! There's four things to do: 1. Enable the computer's EFI password. 2. Enable and set a lock message. 3. Encrypt your HDD using FileVault 2 (No, this will not noticeably slow your computer.) 4. Enable guest mode. Here's how to do it: 1. Enable your computer's EFI password by rebooting your computer while holding down CMD-R. Once in the recovery console, go to the Utilities menu and choose, "Firmware Password Utility". Set a password. DO NOT FORGET THIS EVER!!! Also, when you sell your computer, ENSURE YOU REMOVE IT (or give the password to the new owner). 2. Open up System Preferences and go to "Security & Privacy". Then, go to "General" and click the lock icon at the bottom left. Then, turn on the 'Show a message when the screen is locked' and click 'Set Lock Message...'. Enter something meaningful here, like this: Property of WolfSnap. If found, please call 999-555-1212. Reward offered! 3. Go to the FileVault tab and Turn ON FileVault. Follow the prompts and ensure you make a copy of the decryption key. Make a few copies of it, and store it in a sealed envelope at a friends home/parents home. 4. Go to System Preferences, Users & Groups, and click the padlock icon. Click the 'Guest User' account and ENABLE the Allow guests to log in to this computer. Now that you've enabled all of this, you've essentially made it impossible for a thief to use your computer (except for the very limited guest mode), which ALSO allows you to use the Find my Mac feature in iCloud. Also, there's no way for a thief to reformat your computer and make it usable. It's literally a brick. BUT, since we've set the lock message, there's a (now) permanent way to mark your computer for easy return. After all, a thief wants some money; a reward is still better than nothing. Hope this helps!