Buildup factors for energy deposition in water and aluminum and for exposure in concrete are presented for monoenergetic, point isotropic gamma-ray sources. The buildup fac. tors were evaluated using the method of moments and are tabulated for energies from 0.03 to 10 MeV and distances out to 50 mean -free-paths from the source. Empirical representations of these buildup factors are developed using Berger’s formula. Fitting parameters are tabulated for each material as a function of source energy.