We provide a comparative analysis of the relative growth and morphological sexual maturity in populations of the widespread ghost crab Ocypode quadrata from three different regions of the western Atlantic coast. The populations of O. quadrata selected for this study were located at Punta Arenas Beach, Margarita Island, Macanao Peninsula in Venezuela; at Vermelha do Norte Beach, Ubatuba, State of São Paulo, Brazil; and Atalaia Beach, Aracaju, State of Sergipe, Brazil. We used the allometric technique to determine the size at onset of the morphological sexual maturity of O. quadrata in all samples. The analyzed variables were major cheliped length and height, abdomen width for males and females and gonopod length for males. The values estimated to the size at onset of sexual maturity of each population, expressed in carapace width, were: Vermelha do Norte = 15.46 mm (males) and 19.4 mm (females); Atalaia = 15.77 mm (males) and 17.77 mm (females); and Arenas = 14.46 mm (males) and 20.34 mm (females). The absolute size at onset of sexual maturity varied little among the populations. When the proportional size at onset of sexual maturity (size at onset of sexual maturity/maximum size) was considered, influence of the body growth pattern became evident in Atalaia. The size at onset of sexual maturity and body size and growth in each population seemed to reflect local environmental stimuli rather than those related to latitude.