Accurate atomic scattering cross sections are essential for modeling energetic particle precipitation into the upper atmosphere. Here, measurements of absolute differential cross sections for direct scattering of O+ ions by He, H2, N2, and O2 are reported. The measured cross sections include contributions from both elastic and inelastic scattering processes. Data are presented for 0.5-, 1.5-, and 5-keV projectile energies over the laboratory angular range 0.22¿--4.68¿. Additionally, a simple numerical technique is used to estimate the scattering cross sections for He, N2, and O2 at 0.1 keV. At a given energy, the cross sections for different targets exhibit a high degree of similarity in both amplitude and angular dependence. This observation suggests that the cross sections for targets such as O and H, which are much more difficult to study in the laboratory and for which measurements are not available, may be approximated by an average of the data presented here.