Invited review abstract

We review current ideas about the origin of stellar masses, in the context of nearby star-forming regions. Like the Perseus molecular clouid complex, these generally have prominent filamentary structure with embedded cores and stars , and a few protoclusters with unusually high gas density extending over ~ 1 pc. Over a few Myr each protocluster typically forms a centrally condensed configuration of more than 100 stars, whose mass distribution approximates the stellar initial mass function (IMF). Questions to be discussed include the origin of star-forming cores; relation of their mass distribution to the IMF; core collapse and accretion; termination of infall; and the role of outflows, turbulence and magnetic forces in setting stellar masses.