Abstract The existence of ontogenetic shifts in habitat by marine turtles, and of immature-dominated assemblages in “developmental habitat,” were important concepts first proposed by Archie Carr in 1956. Results of long-term, in-water capture programs in Caribbean Panama (17 yr) and Bermuda (37 yr) allow the testing and refinement of these ideas, in particular the developmental habitat hypothesis for Chelonia mydas, Eretmochelys imbricata, and Caretta caretta. A literature survey reviews worldwide studies on these species, and also incorporates Lepidochelys kempii. The studies in Panama and Bermuda reported in this paper use netting, mark/recapture, laparoscopy, and satellite telemetry to investigate size distributions, maturity status, residency, site fidelity, and developmental migrations of three species of sea turtles at three study sites. Characteristics of benthic developmental habitat of C. mydas, E. imbricata, L. kempii, and, to a lesser extent, C. caretta in the Atlantic Ocean usually include ben...