Project K is a positive youth development programme targeting New Zealand adolescents with low self-efficacy. Project K involves three components: a wilderness adventure, a community challenge and individual mentoring. This presentation describes a longitudinal study aimed at assessing the effects of Project K on self-efficacy, resilience, connectedness, and general psychological wellbeing. Eighty secondary school students were recruited from five schools across New Zealand in a quasi-experimental nonequivalent control group design. Over 14 months, six waves of measurement were completed by Project K participants (n = 49), while four waves of measurement were completed by a control group (N = 31). Data analysis was completed using mixed/multilevel models. Our results suggest that completion of Project K had moderate positive effects on self-efficacy, resilience, and wellbeing, although there was no strong evidence of an effect on connectedness.