You'll need to create a symbolic link from the folder where Mist is looking for the chaindata to the folder where you are storing the chaindata (e.g., on an external drive). You can make a symbolic link with the `MKLINK` command in Windows, there's a good primer on the matter here: http://www.howtogeek.com/howto/16226/complete-guide-to-symbolic-links-symlinks-on-windows-or-linux/?PageSpeed=noscript (A symbolic link is not the same as a Windows shortcut, though it functions similarly) 

Here are directions to do this in Windows Vista, 7, 8 or 10: First, open command prompt in Windows with administrator privileges, then enter:

`mklink /J folder_path_that_Mist_looks_at folder_path_to_your_desired_location`

 In my case with Win8 this command looks something like this: `mklink /J C:\User\Username\AppData\Roaming\Ethereum D:\Etherdata\Ethereum` (I moved my whole Etherdata folder, not just the chaindata folder).

	
The `/J` indicates that you're linking a folder not a file. You do not need to navigate to a particular folder in command to do this.

(Thanks to @BokkyPooBah for his guidance on this [here][1])


  [1]: http://ethereum.stackexchange.com/questions/3338/how-can-i-specify-an-external-harddrive-as-the-download-target-for-the-mist-bloc