We propose to use polarized neutron powder diffraction (XYZ polarization analysis) to measure diffuse magnetic scattering from Y2Os2O7. This cubic pyrochlore insulator does not order magnetically above 2K, but we have evidence from muSR that short-range magnetic correlations develop below about 10K. We shall measure the diffuse magnetic scattering at 2K, 10K and 300K in order to observe how the magnetic correlations develop and correlate the results with our muSR data. The Os4+ paramagnetic moment in Y2Os2O7 derives from an admixture of spin and orbital angular momentum, and forms a geometrically-frustrated sublattice. These are two ingredients that could lead to one of several exotic ground states that have been proposed. Our objective is to determine which, if any, of these ground states forms in Y2Os2O7.