Nine out of 18 adult bluegills exposed for 11 months during a chronic bioassay including reproduction were killed at 80 μg/liter of cadmium in water of 200 mg/liter (as CaCO3hardness. Progeny exposed for 30 days were killed at 90 μg/liter. Adult fish spawned at 239 μg/liter and at 2,140 μg/liter, but most larvae were severely crippled 6 days after hatching at these concentrations. No effects on survival, development, or reproduction were attributable to cadmium at 31 μg/liter. The highest tissue residues were found in liver, intestine and caecum, and kidney. Cadmium concentrations increased with exposure concentration in gill, liver, and intestine and caecum, but not in kidney. At least until more information is available on cadmium toxicity in different water types, chronically toxic and “just safe” continuous exposure concentrations probably can be estimated better by relatively short-term exposures of embryos and larvae than by the use of application factors.