There are a few reasons why you might want to download old versions of Mac OS X. Perhaps you are relying on software you have discovered doesn't work properly in the newest version. Maybe you are using software that requires Rosetta, Apple’s solution for translating PowerPC apps after the Intel transition, or maybe you just don't like the new version of MacOS that you have installed.

Another scenario is that you are a developer and you need to be running multiple versions of Mac OS X so that you can be sure that your software runs correctly on them. Either way, you have questions and we have answers. 

How can I download an old version of Mac OS X?

Go to the Purchased tab in the Mac App Store. Here you can redownload previously purchased versions of macOS and Mac OS X, even if they are older than what's currently installed on your Mac.

It's worth noting that you'll only see old versions of Mac OS X that you've downloaded here - if you never downloaded it, that version will not be in your Purchased section.

Here is how to get an older version of Mac OS X from the App Store (this only works if you've downloaded it in the past):

  1. Open the App Store (choose Store > Sign In if you need to log in)
  2. Click Purchased
  3. Scroll down to find the copy of OS X you want
  4. Click Install

Clicking Install won't actually install the software, but it will download the installer application to your Applications folder.

 How to get OS X Yosemite

Note: You won't be able to simply install an older version of the operating system directly onto a machine running a newer version of OS X or macOS. However, it can be used to upgrade a Mac running an earlier operating system, or you can follow some of the advice below to install the older version on your Mac alongside the current version of macOS.

If you are looking for a way to revert back to an older version of Mac OS X, we explain how you might be able to do this in our how to downgrade from macOS Sierra to El Capitan article, although it seems to be a bit hit and miss.

I can't download my old purchased versions from the App Store

If you know you have previously downloaded the version of macOS you are after, but you aren't seeing it in the Purchased section, try logging out of the App Store then logging in again.

The other possibility is that you downloaded it while logged in to another Apple ID - if you think that might be the case, log in using that ID.

Alternatively, find someone who has downloaded that version of the Mac operating system and ask them to download the installation file for you.

The version of Mac OS X I need is not on the Mac App Store

If you can't see the version of OS X you want in your Purchased list, you've probably not downloaded it, or it may never have been available on the Mac App Store.

The one thing you really mustn't do is go to a torrent site and download a copy of the OS X you want. Just because Apple gives away its software for free, don't think it's fine to just pick up a copy. Pirated copies of Apple software could have been adjusted to allow hackers access to the software and your Mac.

If the copy of OS X that you are looking for was available to download from the App Store (that’s a version of OS X post Snow Leopard) the best option is to find somebody who has had downloaded that version of the Mac OS and is willing to allow you to use their Apple ID to download it again - or will download the install file for you. Luckily the copy of OS X isn't locked to their account so it will install on any Mac.

As we mentioned earlier, some versions of OS X were sold prior to the launch of the Mac App Store. That way of downloading updates and new apps was introduced with Snow Leopard and means that anyone with a Mac running Mac OS X 10.5 Leopard or earlier can’t actually access the Mac App Store to download anything.

The good news is that Apple does allow the purchase of older Mac OSes from its website, so you can get a copy of Snow Leopard and therefore gain access to the Mac App Store.

Apple sells a boxed version of Mac OS X 10.6 Snow Leopard here for £19.99 (at its launch in 2009 it cost £25). In the case of Snow Leopard you will be sent a physical box containing an optical disc - so you will need a CD/DVD drive to install it.

It’s not just Snow Leopard that you can purchase this way - currently you can purchase anything up to OS X 10.8 Mountain Lion on Apple’s website here.

If it’s Mac OS X 10.7 Lion that you are after, it’s available for £19.99 here. Apple will send you a download code to use on the Mac App Store, so you will need to be running Snow Leopard to install it.

If it’s OS X 10.8 Mountain Lion that you need you can buy it for £19.99 here. As with Lion, Apple will send you a download code to use on the Mac App Store, so you will need to be running Snow Leopard to install it.

If the old version of the OS you are after predates Snow Leopard and you have a developer account you might be able to get it from developer.apple.com/downloads. If you search within the OS X category you should see downloads for all versions of OS X, at least from version 10.3 to 10.6. You may be able to access the Developer section of the website, but you will only be able to access certain software downloads if your Apple ID is associated with a paid Apple Developer Program.

If you haven't signed up as a Apple Developer, find out what that entails here. It costs £79 ($99) a year to join the Apple Developer Program and you have to sign a non disclosure agreement.

You could also try looking on Amazon or eBay to see if anyone is selling old versions of the Mac operating system. For example there’s a Full Install of OS X Lion available for £12.99 on Amazon here, and a number of other versions of OS X available. 

How to download Mac OS X Mountain Lion, Snow Leopard and older Mac software

I can't download/install an older version of OS X because I get a warning saying my machine is too new and doesn't support the OS

Just as newer versions of macOS tend to drop support for older Macs, older Macs often can’t support newer versions of macOS This is because the drivers for the hardware on your new Mac simply don’t exist in the old software, so it can't run.

For example, if your Mac was released in 2012, you can download any Mac OS X versions that were supported when that Mac launched, and any versions that have since launched and support that generation of Mac.

For a 2012 Mac, that list should include: Mountain Lion, Mavericks, Yosemite, El Capitan, and macOS Sierra. But you won't be able to download Lion, Snow Leopard or anything older than that.  

If you need to run an older version of OS X, perhaps because you are a developer testing versions of an app on older operating systems, you will need to find an older Mac to run it on.

How to download Mac OS X Mountain Lion, Snow Leopard and older Mac software: iMac G3

How can I run an old version of Mac OS X if the version on my Mac is newer

If your Mac is running a newer version of the MacOS you won’t be able to install an older version on top of it. At least not in a simple way.

  1. You need to start by downloading the installer of the version of OS X that you require from the Mac App Store, you should find it in the Purchases section. Follow the instructions above.
  2. You need to use this installation file to create a bootable installer on an external storage device. This drive needs at least 8GB of space available. Read more about creating a bootable installer here.
  3. Next you need to completely erase everything from your Mac, restoring it to factory settings.
  4. Now re-install the older version of the OS software using the installer you just saved to the external drive.
  5. Now recover your Mac using a Time Machine back up that predates the new macOS installation, assuming you have one.

We have more information about downgrading your version of the Mac operating system here.

These steps aren’t guaranteed to work as there are a number of reasons why you may not be able to install older software on a Mac. For example, if the Mac shipped with a newer version of the software installed than the one you are attempting to install.

A better solution might be to run the older version of the operating system from the external drive or in a partition. We’ll look at those options below.

How can I run an older version of Mac OS X on a external hard drive?

A great way to run an older version of Mac OS X is to do so via an external storage device.

As above, a bootable version of the older version of the OS can be installed on an external hard drive. If you hold Option/Alt down when you start up your Mac you can choose to boot from that drive.

You can read more about how to run an older version of Mac OS X on a external drive here.

Another option is running the older version of OS X in a virtual machine like Parallels or VMware, we look at that next.

How can I install older versions of Mac OS X in a virtual machine

Before we look at how to install a version of Mac OS X on a virtual machine we need to look at Apple’s end user license agreement. This is a legal mine field. Read about Apple's Terms and Conditions and the EULA here.

Since Mac OS X 10.7 versions of the Mac operating system are only licensed to be run in a virtual machine if the host Mac is running the same version. This means that installing an OS X 10.8 VM on a Mac running another version of OS X is a violation of the 10.8 software license agreement. The newest version of OS X that can legally be run in a virtual machine with a different OS X host is Snow Leopard (10.6).

The solution here is too run the server versions of the OS that you require, as long as you have the software license from Apple.

Despite this, VMware Fusion and Parallels do support OS X client as well as server versions.

Another thing to note is that Apple’s end user agreement does allow you to run the Mac OS on two virtual machines and on one computer, but these virtual machines cannot be used for business (unless you’re a registered Apple developer).

Also bear in mind - Macs cannot boot into an OS X version older than the one they shipped with when new, even if it’s on a virtual machine. If you want to run older versions of OS X on your Mac, you need to get an older Mac that can run them.

There are a number of software packages that make it possible to run multiple versions of the Mac OS (and even Windows) on your Mac. These include Parallels, VMware Fusion, Virtual Box. Find out which is best by reading: Parallels, VMware, VirtualBox and Boot Camp compared.

To install an older version of OS X on a Parallels VM download the installer of that version of the Mac OS, create a new VM on your Mac and install the old version of OS X on that VM.

To install an older version of OS X on a VMware Fusion VM the process is similar to that outlined above.

VirtualBox is free, where Parallels and VMware aren’t, but VirtualBox requires using Terminal commands to get OS X installed so it’s a bit more complicated.  

Apple’s Boot Camp also offers the ability to run Windows on a Mac, but you don’t need to run Apple’s Boot Camp to create a partition that will be used for another version of OS X. You can create a partition and install it there. We look at that option below.

Related to virtual machines, you can also run Windows and use Windows apps the same way, read: How to run Windows apps on a Mac and
How to install Windows on a Mac.

How can I run an older version of Mac OS X in a partition?

You can install as many client versions of OS X as you wish on your machine, you just need to create a separate partition for each version. You won’t be able to install a version of OS X that is older than the machine you are using though.

We look at how to run two versions of Mac OS X on separate partitions here.

For information about Apple's terms and conditions for using Sierra read: Should you agree to Apple's terms and conditions