This Mentored Patient-Oriented Research Career Development application (K23) will provide protected time for Dr. Margo Hurlocker to become an independent researcher at the University of New Mexico (UNM) and Center on Alcohol, Substance use, And Addictions (CASAA). Her goal is to develop the expertise to integrate and test implementation strategies within clinical trial designs to improve the treatment delivery system and client engagement in addiction and other behavioral treatment programs. As a first step in developing expertise in addiction implementation science, the candidate proposes an original, mentored research study focused on replacing the comprehensive assessment with an evidence-based intervention (Motivational Interviewing [MI]) during a client’s initial contact with an addiction treatment program to improve client entry, engagement and retention. Addiction treatment programs have some of the highest premature dropout rates and approximately 44% of clients drop out after the intake assessment. The assessment-based intake may contribute to the high rates of client dropout given the emphasis on gathering information rather than exploring client reasons for seeking treatment. This study builds on a large body of literature supporting MI as a prelude to other evidence- based treatments to facilitate treatment engagement, by using an effectiveness-implementation hybrid design to (1) examine the clinical utility of MI at intake on client’s entry and engagement in treatment, and (2) use a mixed-methods approach to evaluate treatment personnel’s’ perspectives of implementation feasibility. Also, in-treatment factors (readiness to change; working alliance) are examined as putative mechanisms of engagement-related outcomes given pre-treatment factors tend to account for a small amount of variance in client dropout. This mentored study will offer hands-on training to help the candidate develop the expertise to establish her own independent addiction research program. With the guidance of her mentorship team, Dr. Hurlocker’s training plan and mentored study are integrated and will promote a comprehensive skill set in the following areas: (1) conducting clinical effectiveness research in addiction treatment programs (Theresa Moyers & Barbara McCrady; UNM), (2) implementation theory and application (Geoffrey Curran; UAMS & Kamilla Venner; UNM), (3) implementation process evaluations (Theresa Moyers; UNM & Geoffrey Curran; UAMS), and (4) advanced quantitative analyses of client and provider data (Katie Witkiewitz; UNM). All mentors will also assist Dr. Hurlocker in grant preparations and submissions throughout the award period. In addition to training at CASAA, Dr. Hurlocker will complete substantive coursework with the Institute for Implementation Science Scholars at Washington University in St. Louis and advanced quantitative coursework at UNM. Collectively, Dr. Hurlocker’s training goals and mentored study are in line with NIDA’s attention to 1...