The ab initio (HF/D95**) optimized geometries and equilibrium molecular polarizabilities have been obtained for 35 hydrocarbons : all-trans straight-chain alkanes to C-15, isobutane, 6 cyclo- and methylcycloalkanes, 8 bicycloalkanes, 4 propellanes, and a tetracyclane. The derivative of the molecular polarizability associated with the stretch of a single CH bond has been calculated for each unique CH. In contrast to expectations of the bond polarizability model, there is considerable variation in the magnitude of the derivatives, ranging from a high of 1.38 x 10(-30) C m/V for the bridgehead CH bond in bicyclo[1.1.1]pentane to a low of 0.908 x 10(-30) C m/V for a methylene CH in bicyclo[3.3.1]nonane. These differences would result in a factor of similar to 2.3 difference in the Raman scattering intensity for the respective CH stretching vibrations. Trends in the equilibrium polarizabilities and in the derivatives are analyzed in terms of molecular structure and charge flow. Principal factors governing the magnitude of the derivative are identified as location, alignment, group strain, and steric hindrance. Averaging of competing effects is also inferred. Implications for the prediction and interpretation of Raman scattering intensities and for the analysis of charge flow in hydrocarbons are discussed.