The Physics case is presented for the use of polarized protons at RHIC for one or two months each year. This would provide a facility with polarizations of ≳50%, high luminosity∼2.0×1032cm−2s−1, the possibility of both longitudinal and transverse polarization at the interaction regions, and frequent polarization reversal for control of systematic errors. The annual integrated luminosity for such running (∼106sec per year) would be ∫Ldt=2×1038cm−2— roughly 20 times the total luminosity integrated in ∼10 years of operation of the CERN Collider (∼10 inverse picobarns, 1037cm−2). This facility would be unique in the ability to perform parity‐violating measurements and polarization tests of QCD. Also, the existence ofp‐pcollisions in a new energy range would permit the study of ‘‘classical’’ reactions like the total cross section and elastic scattering, etc., and serve as a complement to measurements fromp‐p¯ colliders.