Differences in the distributions of v sin i for various samples of B-type stars may reflect different mechanisms of star formation. The overall distribution of v sin i for late B-type stars in clusters at low galactic latitudes is bimodal, but normal class V field stars may have a Maxwellian distribution of v. The spin axes of stars in tightly bound clusters may be preferentially aligned perpendicular to the galactic plane. Early B-type stars in the youngest subgroups of associations may have a Maxwellian distribution of v, but there is a prominent excess of slow rotators among stars in older subgroups and field stars. This excess cannot be entirely accounted for by tidal or magnetic braking during main-sequence evolution.