The current study proposes to extend transdiagnostic treatment research to adolescents by establishing initial pre to post-treatment and follow-up outcomes associated with the use of the Spanish Version of the Unified Protocol for the Treatment of Emotional Disorders in Adolescents (UP-A; Ehrenreich-May, Bilek, Buzzella, Kennedy, Mash, & Bennett, 2016) as a universal school-based preventive intervention.