We determined body size, gonad weight, fecundity, and egg size for two populations of kokanee (lacustrine sockeye salmonOncorhynchus nerka) from two tributaries to Upper Arrow Lake, British Columbia. Embryos and alevins from both populations were incubated at controlled water temperatures (2, 4, 6, 8, and 10°C) to determine survival rates, hatching and emergence times, and alevin and juvenile sizes. Embryo and alevin survival rates were similar between populations, but varied among temperatures; the lowest survival rates occurred at 2°and the highest at 6°C. Time to hatch and emergence varied inversely with incubation temperature. Alevin and juvenile size generally increased with decreasing incubation temperature. Differences in reproductive and developmental biology among populations may reflect adaptations to the specific environmental conditions experienced during spawning and development.