If you downloaded your copy of Windows 10 you'll need to correctly copy it onto a USB Flash Drive. If you purchased your copy of Windows 10 on a USB Flash Drive you can skip to this step.

Be sure to only download Windows 10 from the Microsoft site to avoid malware. I was unable to enter a Windows 7 or 8 product key in the Windows 10 installer (it won't ask if it auto detects Win 7 or 8 previously installed). You can also download Windows 10 as a free download from Microsoft, but you will need a valid Windows 10 product key to activate at some point. I was unable to use Disk Utility or Boot Camp Assistant to properly create the Windows 10 USB Flash Drive from my OS X 10.10.4 Mac as of August 2015. iso disc image to a 4GB or larger USB Flash Drive, and this step is best done from a Windows computer.

Purchase Windows 10 as a download from the Microsoft Store or Amazon. If you buy the Windows 10 Pro version it includes the installers for both the Pro and Home 64 bit versions. Purchase Windows 10 on USB flash drive from the Microsoft Store, Amazon or a local computer reseller. Microsoft makes it easy for existing Windows 7 and 8 users to get a free version of Windows 10 from within Windows, but for a new installation of Windows on a MacBook that has never had a copy you'll want to look at the following methods:

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