Polarization effects have been ignored in most photon transport codes to date, but new technology has created a need for portable, massively parallel, versatile transport codes that include the effects of polarization. In this project, the effects of both linear and elliptic polarization on the angular distribution of coherently and incoherently scattered photons are incorporated into the Monte Carlo transport code Mercury. In Mercury, photons are given a polarization fraction, polarization direction, and a polarization ellipticity. These new variables are tracked throughout each particle's history. They impact and are impacted by interactions with the medium. The determination of how these variables affect the photon's interactions with the medium uses Stokes vectors and the Mueller matrices for coherent and incoherent scattering events. Verification studies were performed comparing results from Mercury against analytical, experimental, and computational results. In all cases, Mercury showed agreement with the expected results. It was also shown that polarization effects are present and potentially significant even in cases where an initial beam is completely unpolarized. Adding polarization effects slowed the code between 10-50% depending on the particular problem. Mercury can now accurately model polarized light.
