The polarization of Venus at 2.2, 3.5 and 4.8 µm, measured through a 4 arcsec aperture at several phase angles, is presented and compared with the predictions of multiple scattering calculations using the optical constants of sulfuric acid. To determine the fraction of light which is thermally emitted, drift scans were made across Venus at 3.5, 4.8 and 8.4 µm. The large positive polarization (∼ 40%) observed at 3.5 µm is consistent with the large imaginary part k of the index of refraction of H2SO4 at that wavelength which minimizes the depolarization from high-order scattering. The lack of observed polarization at 4.8 µm is not consistent with the large value of k there in spite of dilution of the scattered light by a large thermal component. At 2.2 µm Venus has a neutral point and no polarization is observed. Abstract The polarization of Venus at 2.2, 3.5 and 4.8 µm, measured through a 4 arcsec aperture at several phase angles, is presented and compared with the predictions of multiple scattering calculations using the optical constants of sulfuric acid. To determine the fraction of light which is thermally emitted, drift scans were made across Venus at 3.5, 4.8 and 8.4 µm. The large positive polarization (∼ 40%) observed at 3.5 µm is consistent with the large imaginary part k of the index of refraction of H2SO4 at that wavelength which minimizes the depolarization from high-order scattering. The lack of observed polarization at 4.8 µm is not consistent with the large value of k there in spite of dilution of the scattered light by a large thermal component. At 2.2 µm Venus has a neutral point and no polarization is observed.