I assume you're starting from scratch: no accounts set up yet. If you do have accounts, the approach would be different. The simplest approach would be in install TB normally. Then, locate the default profile at c:\yourID\appdata\roaming\profiles . Next, while TB is NOT running, COPY the profile to wherever you want it, and name it whatever you wish, e.g, d:\MYPROFILE. Now, start the profile manager. One way is to click windows key and 'R' key and then enter thunderbird.exe -p . Another way is to right-click on TB desktop icon and adding -p at end of target line, at least a space to right of ".... thunderbird.exe" start TB and on profile manager, click 'create profile', click next, then type in a name, e.g., PROFILE, and click the browse button to select your profile wherever you put it. And your're done. Now, if you want to bypass the profile manager and you are comfortable editing a text file. locate the profiles.ini file in c:\users\.......... roaming\thunderbird and open with notepad. You will see a PATH= statement. Overtype the location with the proper location, e.g., d:\MYPROFILE .