More than 95 per cent of the natural gas in the state of California occurs as "wet" gas with crude petroleum. It is therefore clear that a study of natural gas resources can not be made independently of a consideration of the state's petroleum resources. Figure 1, a map of the oil and gas fields of the southern part of the state, shows with some accuracy their geographic locations and areas, together with their relations to major physiographic subdivisions and cultural developments of the state. Three small fields in this region produce "dry" gas alone. Fields are grouped into four geographical regions. Areas which contribute materially to the state's resources are discussed separately in brief as to discovery, surface and subsurface lithology and stratigraphy, structure, number and depths of producing zones, gas-oil ratios and the estimated amount of gas available from the fully and partially developed zones. Stratigraphic columns of the four regions and structural maps of the producing fields are presented. A tabulated summary of the gas resources of the state appears at the close of the paper.