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[Editor’s note: This article is part of our series of articles on installing and upgrading to Mavericks.]
As I explained in my guide to installing Mavericks, one of the requirements for installing OS X 10.9 is that you already have at least Snow Leopard (Mac OS X 10.6) installed. (Specifically, Mavericks requires OS X 10.6.8 or later.) The main practical reason for this requirement is that Mavericks is available only via the Mac App Store, and the Mac App Store debuted in Mac OS X 10.6—in other words, you need Snow Leopard or later just to be able to purchase and download Mountain Lion.
But once you’ve got your copy of Mavericks, can you install it onto a Mac or an external drive containing Leopard (Mac OS X 10.5)?
The license agreement
The software license you agree to when you install Mavericks states that you can “download, install, use and run for personal, non-commercial use, one (1) copy of [the OS] directly on each Apple-branded computer running OS X Mountain Lion, OS X Lion or OS X Snow Leopard…that you own or control.” In other words, if your Mac shipped with Mountain Lion, Lion, or Snow Leopard, you can install Mavericks. If your Mac shipped with Leopard or Tiger (Mac OS X 10.4), but you later purchased and installed Snow Leopard, Lion, or Mountain Lion, you can install Mavericks. If your Mac doesn’t at least have Snow Leopard installed, you can’t install Mavericks.
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