One common belief about happiness, espoused to varying degrees by both researchers and laypeople alike, is that happiness involves a lack of negative hedonic experiences. In the current investigation, we examine whether individual differences in endorsement of this belief, termed negative hedonic belief, moderate the effects of stress on happiness and several indicators of well-being. It was predicted that because stress involves the experience of negative hedonic states, increased stress would be more robustly associated with decreased happiness and well-being among those endorsing negative hedonic beliefs. Results from three studies utilizing both retrospective and prospective research designs generally support this prediction and suggest that endorsing the belief that happiness involves a lack of negative hedonic experiences is associated with more negative outcomes in response to the experience of heightened life stress.