Nineteen species of caprellid amphipods representing six genera are described for the northern California coast. The study area extended from the Oregon-California border south to Fort Bragg. Twenty-one collecting sites were established and classified as to habitat type. The ranges for the following six species have been extended: Caprella brevirostris, C. greenleyi, C. pustulata, C. alaskana, C. acanthogaster, and Cercops compactus. The latter five species are new to California, and one of these, a new subspecies of Caprella acanthogaster, is described. A key is presented, and correlations between the types of coastal habitat and observed caprellid distribution patterns are discussed.