Reliable data on jaguar population densities are needed to propose appropriate conservation and management strategies, and camera trapping may be effective for estimating the population density of secretive large cats. I determined the population density of jaguars in the Chamela-Cuixmala Biosphere Reserve along the coast of Jalisco, Mexico, through camera trapping and capture–recapture analysis during the dry season of March to June 2008. I applied the half mean maximum distance moved (1/2MMDM) to calculate the radius of the effectively sampled area, and compared this with estimates of the effectively sampled area based on existing data on mean home range of jaguars at the study site. I found that both methods of calculating the effectively sampled area produced similar population density estimates. The widely used 1/2MMDM based on camera-trapping data produced a population density of 5.3 jaguars/100 km2, while calculation of the effectively sampled area based on mean home range produced a population density of 5 jaguars/100 km2. Despite the small size of the 131-km2 Chamela-Cuixmala Biosphere Reserve, jaguar population density was relatively high, suggesting that small, well-protected reserves can be important refuges for jaguars.