The impact of chronic exposure to CO<sub>2</sub>-acidified seawater on survival, growth and development was investigated in the North Atlantic copepod <i>Calanus finmarchicus</i>. Using a custom developed microcosm system fertilized eggs and subsequent development stages were exposed to normal seawater (390 ppm CO<sub>2</sub>) or one of three different levels of CO<sub>2</sub>-induced acidification (3300, 7300, 9700 ppm CO<sub>2</sub>). Following the 28 day exposure period survival was found to be unaffected by exposure to 3300 ppm CO<sub>2</sub>, but significantly reduced at 7300 and 9700 ppm CO<sub>2</sub>. Also, the proportion of copepodite stages IV to VI observed in the different treatments was significantly affected in a manner that may indicate a CO<sub>2</sub>-induced retardation of the rate of ontogenetic development. Morphometric analysis revealed a significant increase in size (prosome length) and lipid storage volume in stage IV copepodites exposed to 3300 ppm CO<sub>2</sub> and reduced size in stage III copepodites exposed to 7300 ppm CO<sub>2</sub>. Together, the findings indicate that a <i>p</i>CO<sub>2</sub> level ≤2000 ppm (the highest CO<sub>2</sub> level expected within year 2300) will probably not directly affect survival in <i>C. finmarchicus</i>. Long-term experiments at more moderate CO<sub>2</sub> levels are however necessary before the possibility that growth and development may be affected below ≤2000 ppm CO<sub>2</sub> can be ruled out.