Optimism is frequently inversely associated with distress; however, less is known about the mechanisms underlying this relationship. Optimism can be defined as having a generalized positive expectancy about the future. The authors hypothesized that a specific expectancy might mediate the relationship between optimism and distress. That model was tested using perceived risk of breast cancer as a specific measure of expectancy and cancer worry as a measure of distress in a community-based sample of 1,366 women. It was hypothesized that optimism would be inversely associated with cancer worry and that perceived risk of breast cancer would mediate the relationship between optimism and cancer worry. Multiple regression analyses revealed that perceived risk partially mediated the relationship between optimism and cancer worry.