Through telephone surveys, written questionnaires, and face-to-face interviews, it was found that people's biggest regrets tend to involve things they have failed to do in their lives. This conflicts with research on counterfactual thinking that indicates that people regret unfortunate outcomes that stem from actions taken more than identical outcomes that result from actions foregone. These divergent findings were reconciled by demonstrating that people's regrets follow a systematic time course: Actions cause more pain in the short-term, but inactions are regretted more in the long run. Support for this contention was obtained in 2 scenario experiments that assessed people's beliefs about the short- and long-term regrets of others and in an experiments that asked Ss about their own regrets of action and inaction from 2 time periods. Several mechanisms that can account for this temporal pattern are discussed.