Drawing upon the expertise of 5 of the country’s leading complex trauma treatment developers, the Complex Trauma Treatment Initiative (CTTI) at Adelphi University’s Institute for Adolescent Trauma Treatment & Training will 1) intensively train multidisciplinary providers to implement and deliver evidence-based Complex Trauma treatments to culturally, ethnically, and racially diverse justice-involved youth (JIY), refugee/asylum-seeking minors (RASM), and trauma-exposed youth in urban and rural high-risk schools, 2) adapt existing interventions and develop innovative and specialized multi-media resources (e.g. youth-led videos, web-based and in-person workshops) for RASM and JIY, and 3) promote sustainability of these practices through the development and refinement of processes and protocols (including clinician certification and creation of internal and national training teams) to embed interventions within child-serving systems. It is well-established that high levels of trauma exposure place youth at greater risk for academic failure and incarceration, yet despite documented findings that JIY, RASM, and youth in rural and urban high poverty areas are among the most trauma-exposed, many of these youth do not receive any trauma-specific interventions. With only 12 (of more than 115) current NCTSN centers working with refugees, and fewer than 20% focusing on JIY in any capacity, the CTTI fills an important gap in serving these vulnerable groups of highly traumatized children and adolescents. The CTTI will have a national reach through collaborations with more than 20 identified partners, including educational systems, state juvenile justice systems, community agencies, and the world’s largest organization serving refugees. Targeting partnerships in 9 of 10 SAMHSA designated regions, the CTTI will work to close the gap for BIPOC youth and youth in more rural areas of the country that historically have been underserved with little to no NCTSN presence. Relying upon implementation science and Learning Collaborative methodology, the CTTI will intensively train partners in interventions that 1) were developed specifically to ameliorate the sequelae of intense, ongoing and/or multiple forms of trauma (i.e. Complex Trauma), and 2) have been identified as Complex Trauma treatments by the NCTSN: a) Structured Psychotherapy for Adolescents Responding to Chronic Stress (SPARCS), b) Real Life Heroes, c) Trauma Adapted Family Connections, d) Integrative Treatment of Complex Trauma, and e) Attachment, Regulation, and Competency (ARC). For the first time since the inception of the NCTSN 5 established Complex Trauma treatments will be joined together in one initiative, thereby enabling a “mapping” of models across various selection criteria that will allow CTTI staff and community partners to select the “best fit” model for each agency. Over 5 years, the CTTI will adapt and develop specialized resources (including Spanish translations), and provide both intensive and broad-based training to more than 10,800 multi-disciplinary providers, extending the delivery of evidence-based trauma-specific practices and improving outcomes for tens of thousands of traumatized youth nationally.