Objective: This study examined the relative contribution of five dispositional mindfulness (DM) facets and two aspects of social support along with sex in predicting psychological adjustment. Participants: Three hundred fifty-three undergraduates (72% female; M = 18.82 years) participated with data collected from September 2014 through March 2016. Methods: Self-report measures of DM, social support, perceived stress, and emotional well-being were completed. Results: Sex and higher scores on specific mindfulness facets (ie, nonreactivity, nonjudging) predicted lower stress and greater emotional well-being. Higher family support predicted lower stress, whereas friend support predicted greater emotional well-being. The mindfulness facets were stronger predictors of adjustment than the social support domains. Females reported higher perceived stress and lower emotional well-being than males, and males scored significantly higher on total mindfulness, nonjudging, and nonreactivity. Conclusions: Results have implications for mindfulness-based interventions with college students such that focusing on the nonjudging and nonreactivity facets may enhance effectiveness.