Happiness is a topic that ignites both considerable interest and considerable disagreement. Thus far, however, there has been little attempt to characterize people’s lay theories about happiness or explore their consequences. We examined whether individual differences in lay theories of happiness would predict empathy. In Studies 1a and 1b, we validated the Lay Theories of Happiness Scale (LTHS), which includes three dimensions: flexibility, controllability, and locus. In Study 2, higher dispositional empathy was predicted by the belief that happiness is flexible, controllable, and internal. In Studies 3 and 4, higher empathy toward a specific target was predicted by the belief that happiness is flexible, uncontrollable, and external. In conjunction, Studies 2, 3, and 4 provide evidence that trait and state empathy are separable and can have opposing relationships with people’s lay theories. Overall, these findings highlight generalized beliefs that may guide empathic reactions to the unhappiness of others.