Which version of Premiere are you using?
I have Premiere 2014 that is associated with Adobe’s Creative Cloud. I upgraded from Mavericks to Yosemite. So far, so good. Actually, all of the Creative Cloud programs are functioning in a reasonable manner. Of course, I haven’t had the time to thoroughly test all of them. But so far, no crashes.
If you are using Premiere Pro CC2014, one of the things that is recommended to do, as read from the Adobe web-site, is configure the “Security & Privacy” (found in the computer’s System Preferences) so that you “Allow apps downloaded from: Anywhere“. If I remember correctly, this was recommended using Mavericks as well. However, if you are using older versions of Premiere Pro, Pre – Creative Cloud, hopefully someone else who was brave enough to venture into Yosemite, with much more know-how, can help you out.