Over the last decade, wilderness therapy research has increased substantially in both quality and quantity and has begun to establish a base of evidence and literature. However, there is still much to be learned about the clients served and their clinical profile. The authors examined diagnostic data from discharge summaries of 929 clients (192 young adults and 737 adolescents) who enrolled in wilderness therapy at four sites across the nation. We explored trends and differences in primary diagnosis and overall prevalence of disorders according to gender and age. Central themes emerged such as the pervasiveness of substance issues, the overwhelming impact of Mood Disorders, and the clinical complexity of wilderness therapy clients. How these findings fit in with industry trends are discussed, as well as the conceptualization of behavioral issues from adolescent to adult populations, variances between adults and adolescents, and gender differences.