The physical processes typically used in the detection of high energy γ rays do not permit good angular resolution, which makes difficult the unambiguous association of discrete γ‐ray sources with objects emitting at other wavelengths. This problem can be overcome by placing γ‐ray detectors on the Moon and using the horizon as an occulting edge to achieve arcsec resolution. For the purposes of discussion, this concept is examined for γ rays above about 20 MeV for which pair production dominates the detection process and locally‐generated nuclear γ rays do not contribute to the background.