We surveyed breeding Black Terns throughout California in 1997 and 1998, following winters of very high runoff. We estimated the state's nesting population at about 4,150 pairs (±30%), of which 47% were in northeastern California and 53% in the Central Valley. The 1,940 pairs in northeastern California were at 60 sites; 59% were at 10 sites and 70% were in Modoc County.