We collect and spectrally resolve photoluminescence from single CdSe nanocrystallite quantum dots. By eliminating spectral inhomogeneities, we reveal resolution limited linewidths < 120μev at 10K. These lines are more than fifty times narrower than what has previously been reported using ensemble measurements. Light driven spectral diffusion is seen as a form of power broadening and may be the cause of surprisingly broad linewidths at room temperature. In addition, we see no evidence of excited state emission or coupling to acoustic phonons.