Accurate estimates of Planktonic Larval Duration (PLD) have become critical to the modeling of larval dispersal and connectivity among ecological communities. Among those species where little information on larval duration is known are the spotted (Paralabrax maculatofasciatus) and barred (P. nebulifer) sand basses, two economically important species that have historically been the focus of marine recreational fisheries off southern California. PLD was determined by a count of the daily growth rings from the otolith core to the settlement check and age from the core to the otolith margin. Size at settlement was estimated by the size of the otolith from its core to the settlement mark based on the otolith size to body size relationship. Based on these significant relationships, mean size at settlement of our specimens was calculated to be 10.2 ± 1.6 mmSL for spotted sand bass and 9.1 ± 1.1 mmSL for barred sand bass. Mean PLD was 32.8 ± 2.2 days with a range from 28 to 37 days for spotted sand bass and 25.8 ± 2.2 days (range 21–30) for barred sand bass. Growth rates for the YOY of each species estimated by calculating the length-to-age relationships were 1.13 mm/day for spotted sand bass and 1.28 mm/day for barred sand bass. PLDs of approximately one lunar month and growth rates of about 1 mm/d seem to be common in those summer spawning fishes from San Diegan Province (warm temperate).