The energy loss and transport of electrons and positrons in gaseous cyclohexane, and solid cyclohexane, benzene, polyethylene, and polystyrene are determined and discussed. A formalism for the energy loss properties of nonrelativistic positrons, analogous to that previously developed for electrons, is presented. This approach makes use of the dipole oscillator strength distributions of the medium, which are constructed here for polyethylene and polystyrene from their optical properties and from atomic X-ray photoabsorption coefficients. inelastic collision cross-sections, mean free paths, stopping powers, energy loss distributions, mean energy losses, and csda ranges are evaluated for electrons in gaseous and solid cyclohexane, solid benzene, polyethylene, and polystyrene. Those properties depending on the zeroth energy moment of the inelastic collision cross-section are similar for the solid media, while those depending on the first energy moment show significant differences. The data for electrons are discussed and compared and contrasted with the results of similar calculations for positrons. For energies greater than similar to1 keV, the energy loss properties of electrons and positrons are similar, but for lower energies there are very apparent differences.