Despite extensive research on regret, relatively little is known about the underlying mechanisms of regret within close relationships. Attachment theory provides a theoretical framework to study regret within close relationships. Specifically, anxiously attached people tend to have negative views of themselves and their past acts, which is likely to result in a higher tendency to experience regret. Attachment security is likely to attenuate this tendency. Two studies provide support for these claims. Study 1 used a correlational design and showed that attachment anxiety is positively associated with the tendency to feel regret within close relationships but not with regrets in other domains. Study 2 used an experimental design and showed that reducing attachment anxiety via attachment security enhancement reduces the tendency to feel regret mainly for participants high in attachment anxiety.