  We study single-spin asymmetries in semi-inclusive deep inelastic scattering
with transversely polarized target. Based on the QCD factorization approach, we
consider Sivers and Collins contributions to the asymmetries. We fit simple
parameterizations for the Sivers and Collins functions to the recent HERMES
data, and compare to results from COMPASS. Using the fitted parameterizations
for the Sivers functions, we predict the single transverse spin asymmetries for
various processes in $pp$ collisions at RHIC, including the Drell-Yan process
and angular correlations in dijet and jet-plus-photon production. These
asymmetries are found to be sizable at forward rapidities
