The complete ontogeny and postlarval growth of Modiolus capax are described for the first time. Spawning was easily achieved by a gradual increase in water temperature (1°C/h) from 26°C to 31–32°C after exposing the breeders to air for 6 h. The veliger stage (103 ± 8 μm) was reached 23–24 h after fertilization and the low umbo stage (165 ± 9 μm) on the fifth day of culture; growth thereafter was temperature-dependent. At 28.5 ± 0.5°C, competent pediveligers (275 μm) were first observed on the tenth day of culture and on the twelfth day at 26.5 ± 0.5°C, but survival was twice (42%) that obtained at 28.5°C. Most larvae settled between 290 and 310 μm; metamorphosis took 3–4 days. For settlement, several suspended artificial substrata were tested; ropes of twisted anchovy fishing nets captured the larger percentage. However, the use of a downwelling system was the most efficient strategy for the settlement of M. capax over artificial substratum. After metamorphosis, the shell hinge slowly moved toward a more posterior position, and at 440 μm the disconch had adventitious serrated hairs. Seed growth was exponential and temperature-dependent. At 28.0 ± 0.5°C, growth ranged from 26–127 μm day⁻¹, and from 24–63 μm day⁻¹ at 24.8 ± 1.7°C. In both cases, survivorship from pediveliger to seed was approximately 80%.