Abstract: Background: Veterans of the United States Armed Forces are at disproportionately high risk for suicide death, requiring indicated strategies to mitigate that risk. Dialectical Behavior Therapy (DBT) is effective for reducing suicide attempts in individuals with emotional dysregulation and repeat suicidal behaviors or self-directed violence, but is a comprehensive, multi-component, resource-intensive treatment. A more resource-efficient component of DBT, the DBT Skills Group as an adjunctive treatment, with therapist consultation team (DBT-SG), has been shown to be as efficacious as comprehensive DBT in non-veteran samples, but its effectiveness and factors affecting its implementation have not been studied in the Veterans Health Administration (VHA). This research aims to assess the effectiveness of DBT-SG among high-risk veterans with recent and repeated suicide attempts and emotion dysregulation while systematically evaluating implementation barriers and facilitators. Methods: This hybrid type 1 effectiveness-implementation study will evaluate DBT-SG effectiveness among veterans at high-risk for suicide attempt with emotion dysregulation using a randomized controlled trial of 18 months duration. Study conditions are 24-session DBT-SG plus full-spectrum VHA mental health treatment-as-usual (TAU), or VHA TAU. Outcomes are assessed at 3-, 6-, 12-, and 18-months post-randomization. Before, during, and after the effectiveness trial, implementation determinants of DBT-SG as an adjunctive treatment in VHA will be assessed using a mixed Methods: evaluation grounded in the Integrated Promoting Action on Research Implementation in Health Services (i-PARIHS) framework. Conclusions: This study will provide evidence for DBT-SG effectiveness for veterans at high risk for suicide and information about barriers and facilitators to support more widespread facilitation of implementing adjunctive DBT-SG in VHA if it is found effective.