The California Black Rail (Laterallus jamaicensis coturniculus) is classified “Rare” by the California Fish and Game Commission, but this secretive rail’s status always has been difficult to assess. Wilbur (1974) and Gill (1977) concluded that records of singing birds in spring and immatures in late summer indicated probable breeding by Black Rails in the San Francisco Bay area. Within recent years, calling Black Rails were located in spring and summer in Solano, Napa and San Joaquin counties (Jurek 1976, Department of Fish and Game files). These findings prompted this study, which began 25 March 1977 and concluded on 14 July 1977. Its purpose was to clarify the status of the species in northern and central California and attempt to identify its habitat requirements.