The peak–end rule is used to explain how people make retrospective hedonic evaluations. This study advances our understanding of its mechanism by identifying the different effects of the rule on such evaluations over short and long retention intervals. The results of two experiments show that (i) respondents constructed their retrospective hedonic evaluations on the basis of the peak and end affects only over a short retention interval, not over a long one; and (ii) respondents relied on episodic information to construct their evaluations over a short retention interval, whereas they relied on both semantic and episodic information to construct their evaluations over a long retention interval. Our study also suggests that the “watershed” between short and long retention intervals is likely to lie between 3 and 7 weeks. Copyright © 2012 John Wiley & Sons, Ltd.