Discusses a sexual irrationality questionnaire (SIQ), a 32-item inventory developed to assess beliefs that might contribute to sexual problems and difficulties with intimacy. 109 college students completed the SIQ and 2 other measures of irrational beliefs. The SIQ showed adequate internal consistency; moderate correlations between the SIQ and both the Irrational Beliefs Test and a relationship belief inventory attested to convergent validity, suggesting that irrational beliefs about sex were separate from but related to both general and relationship-specific beliefs. Factor analyses indicated that the largest proportion of variance in Ss' responses to the SIQ was accounted for by low frustration tolerance; 5 additional significant factors emerged (e.g., fantasies, conformity).