I willreview the latest results regarding measurements of rotation rates forsolar-type stars, low-mass stars, and brown dwarfs in young open clusters andin the field. These results now provide a clear view of their rotationalevolution from birth to maturity. I will show how current models attempt toaccount for the observations, and will highlight their successes andlimitations. The insight we gain from the models on the physical mechanismsthat govern angular momentum evolution during the PMS and early MS will bediscussed. Finally, I will outline some of the major remaining open issues inthe modeling of the rotational evolution of solar-type and lower mass stars.