This study was conducted to determine historical trends in subsidence in the Sacramento-San Joaquin Delta and their environmental controls. In the western Delta, average subsidence rates were 2.3 cm yr-1 from 1910 to 1.5 cm yr-1 from 1952 to 1988. Spatially variability in subsidence was correlated with organic matter content of the soil which in turn was related to the depositional and drainage history of the Delta. Subsidence rates appaeared to be independent of crops grown.