Objective and Design: In a pragmatic, randomised, waitlist-controlled trial we tracked 250 first-year university students who were randomly assigned to 3 months of a mindfulness meditation app (Headspace) to use at their discretion in either semester 1 (intervention, n = 124) or semester 2 (waitlist, n = 126). Main Outcome Measures: Students reported their distress, college adjustment, resilience, self-efficacy, and mindfulness, at 3 timepoints: the beginning of semester 1, the beginning of semester 2, and the end of the academic year. With participants' permission, the university provided academic achievement data and Headspace provided app use data. Results: Evidence for improvements in distress at the beginning of semester 2 was weak (intervention vs. waitlist) and app use was low (M = 7.91, SD = 15.16 sessions). Nevertheless, intervention participants who used the app more frequently reported improvements in psychological distress (-5 points, R2 change = .12) and college adjustment (+10 points, R2 change = .09) when compared to non-users. App initiation and persistence beyond the first week was higher when the app was provided in semester 1 than semester 2 (66.1% vs. 44.4%; 46.0% vs. 32.5%). Conclusion: Headspace use was associated with small improvements in distress and college adjustment in first-year university students. Intervening at the beginning of the academic year may encourage uptake.