Isotropic Raman line shapes provide information about molecular interactions, structure, and dynamics. Such line shapes have been measured experimentally along the liquid-gas coexistence lines for both nitrogen and oxygen. We extend previous theoretical studies of nitrogen Raman line shapes by including in a systematic way the dependence of the bond lengths and dispersion and repulsive force parameters on vibrational coordinates. In so doing we include the effects of vibration-rotation and resonant vibrational intermolecular interactions. The dispersion and repulsive force parameter dependences are crucial for obtaining a quantitative description (and even the correct sign) of the line shift. Using a recently developed intermolecular potential, we perform similar calculations for oxygen. For both oxygen and nitrogen agreement with experimental Raman line shifts and line widths along the liquid-gas coexistence lines is reasonably good. One interesting feature of our results is that the dependence of the dispersion and repulsive force parameters on the vibrational coordinates is developed in such a way as to be directly useful in calculations of vibrational lifetimes.