We provide keys to California’s vegetation that correspond with the revised national classification hierarchy of North American vegetation (Faber-Langendoen 2007, FGDC 2008). The keys for forests and woodlands, shrubs, and herbs lead through a series of couplets to groups of ecologically related alliances. Upon arriving at the list of alliances, choose the alliance that best describes the situation (some alliances exist in multiple places in the key). The alliance names denote the characteristic species for each vegetation type. The corresponding descriptions, grouped in alphabetical order following each key, clarify whether the characteristic species is dominant, co-dominant, or characteristically present in a stand in order to meet the alliance requirements. For definitions of commonly used terms such as “dominant,” “relative cover,” and “characteristic,” sees the Glossary of Commonly Used Terms. The key covers all provisional and full alliances plus semi-natural stands and special stands; it does not include the unranked types, which are found in Appendix 4. The following simple vegetation life form key will enable users to decide which main key to use. For those stands where disturbance or harsh environmental conditions make it difficult to determine which main key is appropriate, we provide some flexibility and place some likely confusable alliances in multiple keys. If stands are not easily keyed, check multiple descriptions and choose the best fit based on the species composition, the description of structure, and other supporting evidence mentioned in the text.