A Comparison of Spin Observable Predictions for RHIC

There have been many versions of spin-dependent parton distributions in the literature. Although most agree with present data within uncertainties, they are based upon different physical assumptions. Some physical models are discussed and the corresponding predictions for double spin asymmetries are shown. A summary of the most feasible measurements in the appropriate kinematic regions at RHIC, which should yield the most useful information about the polarized gluon distribution, is given.