The feasibility of applying the spherical harmonics technique to problems in gamma transport is investigated. The spherical harmonics procedure is described for one-dimensional slab geometry for plane monoenergetic sources. Energy spectra obtained by the P-3 approximation covering a wide range of source energies and materials are compared to moments results for penetrations up to fifteen mean free paths. The comparisons indicate that it is plausible to extend the method to multislab geometry for potential design applications.