Project Abstract This competitive continuation proposal requests renewal of our postdoctoral Ruth L. Kirschstein National Research Service Award Institutional Research Training Program (T32) at UCLA, entitled “Research Training: The Science of Child Mental Health Treatment”, 5 T32 MH073517-14 for 5 years for funding to recruit 3 new postdoctoral fellows per year for a two-year mentored training experience (total 6 trainees per year). No predoctoral trainees are proposed. The unique focus of this training program is on training researchers in clinical translational intervention science for child mental disorders to prepare them to become independent transdisciplinary investigators. Trainees will identify specific domains of mental illness and chose research strategies that advance such research at a variety of levels—treatment mechanisms, biomarkers, efficacy study methodology, and implementation science, touching on a large number of Objectives as outlined in the NIMH Strategic Plan. General goals for the trainees will be to obtain a broad background in current issues in child mental health treatment research; develop expertise in a scientific method for application to studies of child treatment; complete significant independent research in a designated area of research; and develop skills necessary for transitioning into an independent investigator. The program has been very successful, with the majority of graduates retained and advancing in research, and some 50% of funded trainees coming from under-represented minority backgrounds. Research training in this renewal will sharpen the program’s focus on clinical research, examining disorder-related areas from a transdiagnostic framework—disruptive/impulsive/compulsive behaviors, autism and neurodevelopmental disorders, pediatric emotional disorders including self-harm, and other neuropsychiatric disorders. New emphases include training in “big data” science and research on mental health disparities. The core training experience will occur within the trainee’s own research and in their close interaction with primary and secondary mentors and preceptors, and the weekly T32 core seminar. In addition, participation in individually tailored didactic coursework across the UCLA campus, training in the responsible conduct of research, and supplementary coursework and experiences will provide broad and specific knowledge in research approaches. The proposal consists of recruiting 3 new postdoctoral fellows/year with medical or doctoral degrees for a 2-year experience. Postdoctoral trainees will possess training in a discipline relevant to human research and child mental health treatment. The program will benefit from the breadth of active child treatment research at UCLA and from the supplemental training available from a wide variety of departments, programs, research units, and other training activities.