Studies of polarized parton distributions at RHIC

We discuss our studies of polarized parton distributions which are related to the RHIC-Spin project. First, the parametrization of unpolarized parton distributions is explained as an introduction to general audience. Second, activities of the RHIC-Spin-J working group are reported. In particular, preliminary results are shown on the parametrization of polarized parton distributions. Third, we discuss numerical solution of the DGLAP Q^2 evolution equations for longitudinally polarized and transversity distributions. An efficient and accurate computer program is important for analyzing future RHIC experimental data.