The primary study hypothesis is that participation in the Fourth R Healthy Relationships Plus program will be associated with positive growth in treatment participants' psychological well-being from pre-test to 12-month follow-up, as compared to control participants. In secondary analyses, the study will explore if treatment participants report less substance use, peer violence, bullying and dating violence at 12-month follow-up than control participants. Since certain person-level (e.g., sex, personality, executive functioning) and program-level (e.g., implementation quality) variables may moderate treatment-outcome relationships, these associations will also be explored. The final hypothesis is that treatment participants will report better attitudes, knowledge and assertive communication at post-test compared to control participants, and that these improvements will mediate the association between program participation and 12-month outcomes.