Objective: To examine the effects of a Healthy Active Living (HAL) community intervention on moderate-to-vigorous physical activity (MVPA), fruit and vegetable consumption (FVC), and psychosocial mediators of physical activity among students transitioning into university. Methods: Sixty undergraduate students were assigned to reside in either the HAL community or no-treatment control residence and completed questionnaire measures at the beginning and end of the academic year. Results: Students living in the HAL community reported significantly more MVPA (F[1,58] = 19.93, p <0.001, ?p[superscript 2] =0.26) and greater FVC (F[1, 56] = 3.12, p =0.08, ?p[superscript 2] =0.05) compared with controls. Participants in the HAL condition also scored significantly higher in action planning (F[1, 58] = 4.79, p <0.05, ?p[superscript 2] =0.08), partially mediating the effect of the intervention on MVPA. Conclusion: A peer-delivered healthy lifestyles intervention targeting first-year university students appears to be effective in preserving or enhancing health behaviors and cognitions during their transition into university life.