Overdose deaths occur at an alarming pace, particularly among those with criminal legal system (CLS) involvement, and public health professionals continue to seek solutions to reverse this trend. Although empirically supported prevention and treatment interventions for overdose and substance use disorders exist, and a rapidly emerging evidence-based innovations became possible through JCOIN, tools for diffusing evidence-based programs, policies, and practices beyond small-scale efforts are nascent. There is an urgent need for applied models to support large-scale spread and scale-up of evidence-based innovations (EBIs) within criminal legal/public health systems that can bridge knowledge translation between researchers and practitioners and move beyond small-scale adoption of innovations. The Implementation & Translation Research Project (I- Trans) Core will fill this need by creating and testing a model for EBI spread and scale-up for CLS agencies and populations to promote the dissemination and implementation of life-changing strategies. The Implementation Translation Spread and Scale-up Model (I-TranSS Model) will integrate conceptual underpinnings from several other models, including the Consolidated Framework for Implementation Research; Diffusion of Innovation Theory; and Knowledge Translation Complexity Network Model. Building on the experiences in JCOIN 1.0, the team will pursue three new aims in JCOIN 2.0. Aim 1: Develop an implementation knowledge translation model (I-TranSS Model). A key element of the Model is a Translation Spread and Scale-up Matrix, which will be developed by the I-Trans Core, and designed for researchers and practitioners to use to select effective dissemination and implementation strategies that will be applied based on inner and outer contextual factors. JCOIN 1.0 researchers and HEAL researchers in CLS-related studies, research participants in JCOIN 1.0 studies, and other implementation experts will be key to the development of the I-TranSS Model. Aim 2: Generate evidence about effective approaches to translate findings into practice while emphasizing conducting exploratory research on elements of the I-TranSS Model. The I-Trans Core will use the Coaching Extender Platform developed in JCOIN 1.0 and the dissemination and implementation of planned and emergent topics as a learning lab to test key aspects of the I-TranSS Model, including the Translation and Scale-up Matrix. Aim 3: Implement a methods component to document spread and scale-up using quantitative and qualitative methods and identify measures suitable to foster knowledge of effective techniques. This activity will result in an inventory of measurements and/or methods that researchers and practitioners can use to provide feedback on spread and scale-up activities. The I-TranSS Model will be used to frame the design of future implementation research projects. The I-Trans Core will provide opportunities for the participants of the Research Education Core...