To study the effects of ocean acidification we examined the effects of ocean acidification on the embryo and larval stages of the economically important southern Tanner crab, Chionoecetes bairdi. Ovigerous females were reared in one of 3 treatments: control (ambient pH ~8.1), pH 7.8, and pH 7.5 for 2 years. Embryos and larvae in year 1 were from oocytes developed in the field whereas embryos and larvae in year 2 were from oocytes developed under acidified conditions Larvae hatched each year, were also exposed to 3 pH treatments to examine starvation-survival, morphology, condition, and calcium/magnesium content. The carbonate chemistry data included salinity, temperature, pH, alkalinity, dissolved inorganic carbon, CO2, bicarbonate, carbonate, and the saturation states of aragonite and calcite. These values varied according to treatment and season throughout the study.