Undergraduate and graduate students show elevated levels of stress and could thus benefit from mindfulness interventions, but the best way to teach mindfulness has not been established. The present study compared a stress management program that used formal meditations and informal practice (Mindful Stress Management; MSM) to one that used brief mindfulness exercises and informal practice (Mindful Stress Management-Informal; MSM-I), and a wait-list control. MSM participants exhibited significant within-group changes on all measures, and when compared to the wait-list control, greater levels of mindfulness, decentering, and self-compassion, as well as lower stress. Students in MSM-I had significant within-group changes on a subset of measures, and greater mindfulness and self-compassion compared to the wait-list. MSM participants showed more improvement in self-compassion, psychological inflexibility, and stress than did those in MSM-I. Mediational analyses found increases in one facet of mindfulness and self-compassion, and decreases in worry mediated reductions in stress for MSM participants, while no mediator reached significance for MSM-I. Finally, no significant relation between amount of formal meditation and informal practice and reductions in psychological distress or increases in mindfulness was found. Results suggest that a program with formal meditations and informal practice may be a more promising intervention for university student stress than one with brief mindfulness exercises and informal practice.