--- - |2+ Abstract Objective This study evaluated a 4‐week web‐based acceptance and commitment therapy (ACT) mental health promotion program called YOLO (You Only Live Once) for university students. Method A total of 130 participants were randomized to one of three intervention groups investigating varied program delivery methods. Primary outcomes assessed: depression, anxiety, stress, well‐being, self‐compassion, alcohol use, and life satisfaction. ACT processes assessed: acceptance, cognitive fusion, education values, valued living, and mindfulness. Results Improvement on the primary outcomes and ACT processes did not differ among the three intervention groups. Analyses showed significant improvements on all primary outcomes (except alcohol use), and on all ACT processes. All ACT processes mediated changes on one or more primary outcomes in the intent‐to‐treat sample. Intervention effects were consistent on most primary outcomes and ACT processes across three sample groupings. Conclusions These preliminary findings provide support for a web‐based ACT mental health promotion program for university students. - Journal of Clinical Psychology, EarlyView.