As stated, 100 stealing, but this does not have to be real skill. I am training (yes, still training) my thief by stealing the stealables. I ate a 110 stealing scroll I had, jeweled up to about 108 skill, and off i have been. Good gains running around and grabbing stuff, and it is a lot more fun than sitting in fel with just my packy to talk to (global chat not withstanding).