Previous work has shown that preferences are not always stable across time, but surprisingly little is known about the reasons for this instability. I examine whether variation in people’s emotions over time predicts changes in preferences. Using a large panel data set, I ﬁnd that within-person changes in happiness, anger, and fear have substantial effects on risk attitudes and patience. Robustness checks indicate a limited role of alternative explanations. I further address potential endogeneity concerns by exploiting information about the death of a parent or child. This identiﬁcation strategy conﬁrms a large causal impact of emotions on preferences.