The origin, distribution, and engineering properties of calcareous soils of the southwestern United States are reviewed. The influence of climatic conditions on formation is discussed. A classification system is outlined in which detailed descriptions of soil masses and their discontinuities are made in test pits or trenches. Procedures of investigation which emphasize the use of standard penetration, plate bearing, and pressure-meter tests and seismic surveys are outlined along with bearing capacity and elastic settlement analysis methods. Typical geotechnical properties from in situ tests and settlement records are presented.