This paper discusses the philosophy and major aspects of the geology training of the Apollo 15, 16, and 17 astronauts. This training concentrated on monthly field trips that were intended to develop the crew's observational skills in recognizing basic geologic structures and rocks and translating observations into an interpretative framework for local geologic evolution. Individual field trips became increasingly mission-like as their training matured. The crews worked with predetermined traverses and progressively added diverse operational aspects, such as proper usage of sampling tools, photo-documentation of pertinent features and rocks, simulation of space-suit mobility, and use of a roving...