Here's another quick option to do a clean install of OS X Mavericks without an external drive. After you are done with the first steps here is what disk utility will show: 1. Open Disk Utility and select your primary drive. (500.11 GB Drive in the image). Click partition and change the Partition Layout to include another partition. Make it as small as possible (8 GB should be a gracious plenty - i went 16 to be safe). The type should be Mac OS Extended (Journaled). 2. Name it "Untitled" if you want the next steps to be easier, but you can adjust the terminal command to whatever you want in the following steps. When it is done the partition will be renamed so "Untitled" is just fine. Click "Apply" and don't worry you are adding a partition not deleting anything. Don't proceed if you don't think your doing this right. 3. Open a Terminal window use the same method detailed here: http://forums.macrumors.com/showthread.php?t=1649986 to create a bootable install media. I would recommend checking /Volumes to make sure that your new partition "Untitled" is showing up. Code: cd /Volumes ls -al If you see the partition then you are ready to create the Mavericks Install Partition. 4. Here is the next step: Code: sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Mavericks.app --nointeraction This will create the bootable partition to install Mavericks. Takes a few minutes. If you named the partition something different just modify the "/Volumes/Untitled" part to match the correct location. 5. When it is done you can proceed with the steps for making a clean install of Mavericks. Backup. Reboot and hold the Option key down. Choose the "Install OS X Mavericks" partition. Njoy.