The reproductive season and first-maturity size of the blue lobster Panulirus inflatus were determined at the “Bahía de Loreto” National Park, Gulf of California. Two hundred fifty-six females were analyzed, finding that the onset of gamete development took place in February. The incubation season started in April and ended in November. The highest percentage of ovigerous females was observed in October (88.9%). Histological analysis of gonads revealed two peaks of gonad maturity, in May (75%) and August (75%). Temperature was positively correlated to the percent ovigerous females (r_s = 0.85, P < 0.05) and with the percent ripe females (r_s = 0.73, P < 0.05). The individual first-maturity size was 49.5 mm CL, whereas at a population level it was 80 mm CL, this being proposed as the minimum fishing size. The incubation period was estimated at 2–3 wk, and the histological evidence suggests that each female may spawn more than once and may undergo more than one incubation period during the reproductive season. The reproduction pattern at the Bahía de Loreto National Park in the Gulf of California is discontinuous, likely because the environmental conditions in this zone are more variable than in tropical regions. This feature should be taken into account by the Mexican government when regulating the exploitation of this resource in the study area.