Formation and evolution of disks around classical Be stars

I review models for formation of Be star disks, with particular emphasis on the role of rapid stellar rotation in providing basis for launching stellar material into circumstellar orbit. Two key questions are: 1) How close must the rotation be to the critical rate at which material at the equtorial surface would effectively be in orbit? and 2) What mechanism(s) (e.g. radiative driving, magnetic torquing, pulsational overshoot) might provide the final boost of material from the surface into an orbiting disk? I also discuss the subsequent evolution of disk material, with emphasis on outward diffusion vs. radiative and/or wind ablation as possible destruction mechanisms that might explain the episodic disappearance of the signature disk emission lines in some Be stars.