I just got around to upgrading to Mavericks and thought I'd add my 2 cents' worth. The software still works, with 3 exceptions, two of which already popped up in Mountain Lion. 1) DVD's burned within Studio Pro seem to be fine, but they always stall about 3/4 through. The work-around is to print the DVD folder from Toast Titanium. My guess is that StudioPro can't keep up with the disk drive. 2) It is impossible to reset the standard size for subtitles, which is much too large. That's because the change font dialogue box in preferences brings up Font Book, which always crashes the program! Workaround is to convert stl subtitles to text and insert instructions above the subtitles for fontsize, font, and color. This overrides the presets, and you'll find spruce-micro formats in the manual. 3) The new problem, as I've seen reported here, is that pull down menus for changing buttom colors are now blank. This is less of a pain if you write out the order of the colors that used to be there. To save you time, here they are: red, black, blue, white, pink, aquamarine, light green, yellow, magenta, orange, purple, green, dark blue, light purple, olive, brown-red. Hope this helps!