The yellowlegs shrimp Penaeus californiensis is an oceanic species that approaches the coastal zone for its reproduction. However, in the southern Gulf of California, this species also enters coastal lagoons to grow and reproduce. To test the hypothesis that the growth of P. californiensis differs between these two environments, monthly samplings of shrimp were made in the interior of the Navachiste coastal lagoon and its adjacent marine area. To determine growth, age groups were identified using the size structures over time. Five cases of the Schnute model were adjusted to the data, and the best case was selected using a multi-model selection approach. A sigmoid-shaped curve best represented the female data (case 2), and the inverted exponential curve (case 5; equivalent to the Von Bertalanffy growth function) was best for males. Average growth differed between sexes (p = 0.0097) but not between environments (p = 0.559).