The Δ14C of surface water dissolved inorganic carbon (DIC) in the Southern California Bight was compared to Δ14C as recorded by the sterols in Santa Monica and Santa Barbara Basin sediments. All of the C26, C27, C28, and C29 sterols as well as dinosterol had 14C concentrations equal to surface water DIC, indicating that all of the major sterols were derived from phytoplanktonic production. There is no detectable terrestrial component. Their tracer capability was confirmed by comparing the bomb 14C-derived change in surface water Δ14CDIC with the change in Δ14Csterol. The prebomb Δ14CDIC was -82?, and prebomb sterols averaged -75¿19?. The Δ14C value in 1996 was +71?. Eighteen measurements representing eight different sterols from the sediment-water interface of both Santa Monica and Santa Barbara Basins averaged +62¿23?. When three of these values were eliminated because of suspected contamination, the remaining data averaged +71¿12?. The entire compound class could serve as an excellent proxy for the 14C concentration of ocean surface waters. ¿ 2000 American Geophysical Union