Ocean and coastal acidification is occurring due to uptake of atmopsheric CO₂, as well as nutrient-fueled respiration in some estuarine and costal environments. Multiple stressors, influenced by human activity, affect the patterns and severity of acidification. Temperature, deoxygenation, and changes in food webs are particualarly important co-stressors. Development of a theoretical underpinning that considers physiological, ecologial, and evolutionary perspectives to address the mutiple stressors is needed. A wide variety of research approaches is a logical and promising strategy for improving the understanding of acidification and its impacts.