This study used mixed methods to examine the effects of an Australian outdoor adventure intervention on youth-at-risks' life effectiveness, mental health, and behavioural functioning. The sample consisted of 53 adolescents who completed a Catalyst program conducted by the Queensland Police-Citizens Youth Welfare Association, a non-profit organisation, in Queensland, Australia. The program involved 15 programming days over a 10 -12-week period. There were small to moderate shortand longer-term improvements in life effectiveness, psychological well-being, and several aspects of behavioural conduct. There were no positive longer-term impacts on psychological distress and some aspects of behaviour. Thematic analysis of 14 participant interviews identified six major themes: overcoming challenging backgrounds, contending with adversity, personal development, social development, motivation to work for change, and a more optimistic outlook on the future. Further research utilising a comparison group, multiple sources of data, and a larger sample could help to qualify results and increase generalisability.