Counterfactual thinking often involves “if only” thoughts about how a negative outcome may have turned out better. Regret is associated with counterfactual thoughts which undo one‟s own actions. We proposed that: (1) if giving an external reason for an action makes it harder to mentally undo, then providing an external reason will result in less regret for an action, (2) an individual‟s attributional style would mediate this effect, and (3) reasons for action and attributional style may influence anticipated regret. One hundred psychology undergraduates completed an attributional style questionnaire and responded to three counterfactual scenarios and three anticipated regret scenarios. Surprisingly, regret was rated significantly higher when an external reason was given for action than when an internal reason was given for action, attributional style attenuated the effect of reason condition on regret, and there were no significant effects of reason for action or attributional style on anticipated regret. Our findings suggest that external reasons need to be sufficiently compelling to make them harder to mentally undo, and a more even distribution of people with internal and external attributional styles is necessary to examine the influence of attributional style on regret and anticipated regret.