Wilderness-adventure therapy has gained increasing interest in Australia in recent years. It has been found to be of particular use for addressing core mental health problems of adolescents at risk of adult mental health problems and suicide. However, there are few, if any models which make a clear theoretical rationale for HOW wilderness-adventure therapy interventions should be made and which relate to models explaining the etiology of mental health problems. In order to answer the question “what intervention for which client?” a thorough developmental understanding needs to be made. An eclectic model of wilderness-adventure therapy intervention is outlined based on a comprehensive developmental understanding. The Brief Intervention Program and case studies are presented to illustrate this approach.