Abstract In response to PAR-20-080, NIMH Mentoring Networks for Mental Health Research Education, the Center for Mental Health Services at the Brown School of Social Work at Washingon University was recently awarded a second renewal of the Implementation Research Institute (IRI). This grant will provide five years of support to respond to training demand, continue scientific leadership to the field, and empower a new generation of leaders in implementation science for mental health services research. This network will extend in creative new ways the Implementation Research Institute (IRI, NIMH R25 funding 2009-2015, 2016-2019), which has successfully trained 87 new mental health implementation researchers. Implementation science is critical for mental health where most Americans with mental disorder receive sub-optimal care due in large part to challenges in the implementation, sustainability, and scale-up of evidence-treatments. Training demand far outweighs supply but only a handful of programs train implementation researchers and only the IRI in mental health. Because most individuals with mental disorder suffer co-occurring problems—many of which involve substance abuse—and because the substance abuse treatment field suffers similar lags in the uptake of evidence-based practices, we propose to once again extend the IRI through NIDA supplementary funding to prepare two new fellows per cohort (total of eight new fellows during a five year supplement) for implementation science that incorporates substance abuse services. NIDA can leverage the already developed training program and infrastructure design and through a three year supplement, benefit from having 8 new investigators trained (over five years) for implementation research in drug abuse. We seek, therefore, funding for the IRI costs for two fellows per IRI cohort. Our aims for the proposed NIDA supplement are: 1. To provide substantive and methods training for implementation research for substance abuse issues involved in the delivery of behavioral health care. 2. To enlarge the existing collaborative of scholars by NIDA fellows, two core faculty members (one existing core faculty member and one core faculty designee who will be mentored by and then replace the existing core faculty during the projects transition) and expert faculty members who will bring expertise in implementation issues specific to substance abuse treatment. 3. To support IRI NIDA fellows’ learning through learning visits to NIDA or NIH-funded research sites, and participation in distance learning activities. 4. To systematically and objectively evaluate these educational training efforts for short term and lasting effects, including fellows’ scholarly publications and successful grant proposals in implementation science. Impacts will occur through scientific publication and submission of competitive NIH grant proposals on mental health and substance abuse implementation science questions with potential to improve the...