The present study is designed to take a new approach to studying gender differences in reactions to partner infidelity by measuring attitudes toward partner infidelity. No previous studies have directly examined attitudes toward partner sexual versus emotional infidelity, nor have studies assessed the strength of these attitudes. Thus, this study was designed as an initial investigation of overall evaluative differences between men and women. It was found that women held significantly more negative attitudes towards emotional infidelity than did men, with no gender differences in attitude held towards sexual infidelity. For sexual infidelity, more positive attitudes toward partner sexual infidelity were associated with lower reported distress for both men and women, with the relationship being significantly more pronounced for men. For emotional infidelity, attitude strength moderated the relationship between attitude towards emotional infidelity and distress about emotional infidelity. There was a significant relationship between attitudes toward partner emotional infidelity and distress when attitude strength was high but not when attitude strength was low.Department of Psychological ScienceThesis (M.A.