Abstract: Although there has been a tremendous amount of research attention on differences in reactions to sexual infidelity and emotional infidelity, there is a lack of information available as to how the two constructs overlap with respect to actual behavior, how expectations for distress vary by behavior, and how sexual and emotional content influence expectations for distress. In order to address this issue, we asked participants to rate 50 behaviors on the extent to which each would constitute sexual infidelity and, separately, emotional infidelity. Participants also rated the degree to which they would be upset if their partner performed the behavior, which enabled us to determine the relationship between views of sexual infidelity, emotional infidelity, and anticipated distress. As predicted, ratings of sexual infidelity and emotional infidelity for the 50 behaviors were largely independent. In agreement with past research, ratings of emotional infidelity were stronger predictors of distress for women than for men, whereas ratings of sexual infidelity were overall stronger predictors of distress for men than for women. Furthermore, ratings of sexual infidelity were overall stronger predictors of distress than ratings of emotional infidelity for both women and men. However, ratings of sexual infidelity were overall stronger predictors of ratings of emotional infidelity for men than for women. The results generally support predictions derived from an evolutionary perspective, elaborating upon the existing understanding of sex differences in anticipated reactions to infidelity.