Palynomorphs in the rhythmites of the Santa Barbara Basin record the response of vegetation to paleoecologic changes of the past 12,000 yr and also reflect fluviomarine changes. Upland coniferous communities dominant in the early part of the record (∼12,000 to ∼7800 B.P.) were succeeded in importance by lowland and cismontane communities in which Quercus and Asteraceae reached optimal development ∼5700 B.P. Subsequently, chaparral and coastal sage scrub associations became increasingly important, particularly since ∼2300 B.P. Inferred climatic fluctuations involve the replacement of wet, cool conditions by warmer, drier climate culminating at ∼5700 B.P.