AbstractGrowth of Crocodylus moreletii, an endangered species, was observed under protected conditions in the native range, from hatching through the third year of life. The goal of this project was to provide baseline growth data for eventual comparison with data from specimens reared in thermally controlled zoo facilities. Length increase averaged 1.6 cm/mo in our study. Under farming conditions in Mexico, however, C. moreletii increased in length by 2.4–3.0 cm/mo. Hence, we suspect that specimens raised under zoo conditions will exceed our values and approach the latter ones, as is the case for American alligators raised in controlled conditions. © 1995 Wiley‐Liss, Inc.