Pairs of Sepiola atlantica maintained in aquaria at ∼17°C successfully mated in the “male parallel position” for between 21 min and 77 min. Over a period of several weeks after mating, female S. atlantica laid egg masses containing 8–161 eggs. At 14.4°C, embryonic development took 33 days and the hatching phase lasted for 23 days (mean hatching success, 32%). Hatchlings emerged from the eggs at a mean dorsal mantle length (DML) of 1.91 mm and entered a pelagic paralarval phase lasting 6 days. Ten to 20 days after hatching, the internal yolk sac became exhausted, whereupon hatchlings were fed ad libitum on wild-caught Zooplankton at a density of ∼90 organisms/L or with enriched adult Anemia (density, 50 organisms/L). Hatchlings maintained on the Artemia diet all died within 38 days, whereas ∼38% of those fed on Zooplankton survived to this point, and the remaining juveniles subsequently attained adulthood when reared on a diet of Crangon crangon. These laboratory-reared juveniles matured and successfully mated, but the females did not lay any eggs. Females subsequently died 230–250 days after hatching and 10–19 days after mating, at a DML of between 21.7 mm and 23.2 mm, whereas the smaller males died 265–293 days after hatching (DML, 17.4–21.4 mm). Growth (increase in DML) of S. atlantica had 2 phases. Growth during the first 120 days was relatively slow at 0.05 mm/day (0.043 mm/day in males and 0.055 mm/day in females), increasing slightly thereafter to day 210, after which growth leveled off. These data indicate that S. atlantica has a similar life cycle to other scpioids.