When you start Windows 8 in Safe Mode, you start it with only the processes absolutely necessary for Windows to be usable. If Windows 8 does start properly in Safe Mode, you can then troubleshoot to see what driver or service might be causing the problem that's preventing Windows from starting normally.

Safe Mode in Windows 8 is accessible from the Startup Settings menu, itself found on the Advanced Startup Options menu. So the first thing to do is to open the Advanced Startup Options menu:

See How To Access Advanced Startup Options in Windows 8 for instructions on several different ways to open this very helpful menu of repair and troubleshooting tools.

Once you're on the Advanced Startup Options menu (shown above) then move on to the next step.

Note: Starting Windows 8 in Safe Mode is identical in both the Pro and standard editions of Windows 8 and Windows 8.1.

The Windows 8 Safe Mode Catch-22

Of the six methods for opening Advanced Startup Options outlined in my linked instructions above, only methods 1, 2, or 3 allow access to Startup Settings, the menu that Safe Mode is found on.

Unfortunately, those three methods only work if you have access to Windows 8 in normal mode. The irony of course is that few people who need to start in Safe Mode can start Windows 8 normally!

The solution is to open Command Prompt from the Advanced Startup Options menu, which you can do using any of the six methods, and then execute some special commands to force Windows 8 so start in Safe Mode on the next reboot.

See How To Force Windows to Restart in Safe Mode for complete instructions. You won't need to follow this tutorial if you start Windows 8 in Safe Mode that way.

Tip: If Windows is working fine for you right now but you still want to start Windows 8 in Safe Mode, another way is to make boot option changes from the System Configuration utility. See How To Start Windows in Safe Mode Using System Configuration, in which case you can skip this tutorial entirely.

What About F8 and SHIFT+F8?

If you're familiar with previous versions of Windows like Windows 7, Windows Vista, or Windows XP, you may remember that you could force the loading of what was then called the Advanced Boot Options menu by pressing F8. This is no longer possible in Windows 8.

In fact, even the widely publicized SHIFT+F8 option, which supposedly works to force Advanced Startup Options to appear (and ultimately Startup Settings and Safe Mode), only works on very slow computers. The amount of time that Windows 8 looks for SHIFT+F8 is so small on most Windows 8 devices and PCs that it borders on impossible to get it to work.

Now that the Advanced Startup Options menu is open, titled with Choose an option, touch or click on Troubleshoot.

Note: Advanced Startup Options may have more or less items to choose from than the one shown above. For example, if you don't have an UEFI system, you won't see the Use a device option. If you are dual-booting between Windows 8 and another operating system, you may see a Use another operating system option.

On the Troubleshoot menu, touch or click on Advanced options.

Tip: Advanced Startup Options contains a number of nested menus. If you need to back up to a previous menu, click the small arrow next to the menu's title.

On the Advanced options menu, touch or click on Startup Settings.

Don't See Startup Settings?

If Startup Settings isn't available on the Advanced options menu, it's likely due to the way in which you accessed Advanced Startup Options.

See How To Access Advanced Startup Options in Windows 8 and choose method 1, 2, or 3.

If that's not possible (i.e. your only options are 4, 5, or 6) then see How To Force Windows to Restart in Safe Mode for help. You might too want to take another look at The Windows 8 Safe Mode Catch-22 section from Step 1 in this tutorial.

On the Startup Settings menu, tap or click on the small Restart button.

Note: This is not the actual Startup Settings menu. This is simply the menu, by the same name, from which you choose to exit Advanced Startup Options and restart into Startup Settings, which is where you'll be able to boot Windows 8 into Safe Mode.

Wait while your computer restarts. You don't need to do anything here or hit any keys.

Startup Settings will come up next, automatically. Windows 8 will not start.

Note: Obviously the image above is an example. Your screen may show your computer maker's logo, a list of information about your computer's hardware, some combination of both, or even nothing at all.

Now that your computer has restarted, you should see the Startup Settings menu. You'll see a number of advanced ways to start Windows 8, all aimed at assisting you in solving a Windows startup problem.

For this tutorial, however, we're focusing on your three Safe Mode choices, #4, #5, and #6 on the menu:

Enable Safe Mode - This is your "standard" Safe Mode option and should probably be your first try.
Enable Safe Mode with Networking - This option is identical to Enable Safe Mode but the few extra processes necessary to access your network and the Internet are also loaded.
Enable Safe Mode with Command Prompt - This option is also identical to Enable Safe Mode but instead of the standard Explorer interface, Command Prompt is loaded instead.
Choose the Safe Mode option you want by pressing either 4, 5, or 6 (or F4, F5, or F6).

Tip: You can read more about the differences between these Safe Mode options, including some advice on when to choose one over another, on my Safe Mode: What It Is & How To Use It page.

Important: Yes, unfortunately you will need a keyboard attached to your computer if you want to make a choice from Startup Settings.

Next you'll see the Windows 8 splash screen.

There's nothing to do here but wait. Next up will be the login screen you normally see when your computer starts.

To start Windows 8 in Safe Mode, you'll need to login with an account that has administrator privileges.

In most cases, that's probably you so just enter your password as you normally do.

If you know you do not have administrator level access, login with another account on the computer that does.

Wait while Windows 8 logs you in.

Next up is Safe Mode - temporary access to your computer again!

Assuming everything went as expected, Windows 8 should have started in whatever Safe Mode option you chose back on Step 7.

As you can see above, the Windows 8 Start screen doesn't start automatically. Instead, you're taken immediately to the Desktop and a Windows Help and Support window appears with some basic Safe Mode help. You might also notice the words Safe Mode at all four corners of the screen.

Now that you can access Windows 8 again, even if it is restricted in some ways thanks to being in Safe Mode, you can backup important files, troubleshoot whatever startup problem you were having, run some kind of diagnostics - whatever it is you need to do.

Getting Out of Safe Mode

If you've started Windows in Safe Mode using the method I've outlined in this tutorial, assuming you've fixed any startup problem you were having, Windows 8 will start normally (i.e. not in Safe Mode) the next time you restart your computer.

However, if you used some other method to force Windows 8 into Safe Mode, you'll need to reverse those changes or you'll find yourself in a "Safe Mode Loop" where, even if you're not having a startup problem, Windows 8 will start in Safe Mode every time you turn on or restart your computer.

I explain how to reverse those actions in my How To Start Windows in Safe Mode Using System Configuration and How To Force Windows To Restart in Safe Mode tutorials which use the System Configuration tool, and the bcdedit command, respectively, to force Windows 8 into Safe Mode on every restart.