CONTEXT: Speculation in public discourse suggests that sexual encounters outside a committed romantic relationship may be emotionally damaging for young people, and federal abstinence education policy has required teaching that sexual activity outside of a marital relationship is likely to have harmful psychological consequences. METHODS: In 2003-2004, a diverse sample of 1,311 sexually active young adults (mean age, 20.5) participating in a longitudinal study in Minnesota completed a survey including measures of sexual behavior and psychological wellbeing. Chi-square tests were used to compare the prevalence of recent casual partnerships by selected demographic and personal categories. General linear modeling was then used to compare mean levels of each psychological wellbeing measure between those reporting recent casual partners and those reporting committed partners; partner type was measured both dichotomously and categorically. RESULTS: One-fifth of participants reported that their most recent sex partner was a casual partner (i.e., casual acquaintance or close but nonexclusive partner). Casual partnerships were more common among men than among women (29% vs. 14%), and the proportions of male and female respondents reporting a recent casual partner diff ered by race or ethnicity. Scores of psychological well-being were generally consistent across sex partner categories, and no significant associations between partner type and well-being were found in adjusted analyses. CONCLUSIONS: Young adults who engage in casual sexual encounters do not appear to be at greater risk for harmful psychological outcomes than sexually active young adults in more committed relationships.