A study was made of a number of rock art sites in California to determine which pigments had been used by the Chumash Indians. The study was based on pigment microsamples and rock art fragments excavated from site debris. The techniques of examination employed in the study were polarized light microscopy, environmental scanning electron microscopy, electron microprobe analysis, colour recording on site and X-ray powder diffraction. The pigments identified by this study include yellow ochre, red ochre, wood charcoal, halloysite ( a white clay) and a white which is probably shell white. The mineral crusts associated with the rock art surface were also studied and gypsum was found to be a common component, together with the calcium oxalate, whewellite. The potential alteration of carbonate pigments to gypsum is inferred from the study. The paper is illustrated with examples of deteriorated rock art and with cross-sections from sites discussed, particularly Carneros Rock and Painted Rock. -- CAL