The abundance of the long-beaked common dolphin (Delphinus capensis) is estimated from data collected during a 2009 ship-based line-transect survey. The survey was designed to provide fine-scale coverage of the known range of D. capensis along the California and west Baja California coasts. Estimates of D. capensis abundance presented are the highest to date for California waters and may reflect a combination of improved survey design for this species and increasing numbers of D. capensis in state waters. Estimates of D. capensis abundance within California waters are 183,396 (CV = 0.41, 95% CI 78,149 − 379,325) animals. An additional 95,786 (CV = 0.47, 95% CI 36,881 − 209,507) D. capensis were estimated in Baja California waters from the U.S./Mexico border south to the tip of Baja California. Total estimated abundance of D. capensis in California and Baja California west coast waters is 279,182 (CV = 0.31, 95% CI 148,753 − 487,323) animals.