The gravitational attractions of bodies in the crust and upper mantle offer important clues to the geologic evolution and anatomy of the continents. Regional gravity maps prepared from millions of observations provide a density and uniformity of coverage that can put other more isolated geophysical studies into a broader framework. Reliable and efficient instruments for collecting gravity observations have been available for many decades. Gravity reduction procedures are now fairly standardized, although misconceptions exist, and it is easy to lose sight of the end goal in the multiple reduction steps. In the last decade, computers have greatly facilitated the presentation and interpretation of large regional data sets. Numerous mathematical inversion techniques have been described in the literature, although for many purposes the best interpretive tool still remains the construction of simple, forward two-dimensional models, constrained by as much geological and geophysical information as can be obtained.