PROJECT ABSTRACT An often-overlooked consequence of the opioid epidemic in the United States is its health impact on substance use providers (SUPs), such as addiction therapists, peer recovery specialists, and case managers. The opioid epidemic has strained addiction treatment services, and the US will likely fall 250,000 SUPs short of the number needed to address the opioid epidemic by 2025. Workforce turnover contributes substantially to this shortage, driven in part by SUP exposure to vicarious trauma. Vicarious trauma refers to the “second hand” trauma transmitted when interacting with people who experienced trauma “firsthand.” Among social service professionals, vicarious trauma is associated with the development of depression, anxiety, and post-traumatic stress. The SUP workforce is likely particularly vulnerable to vicarious trauma since over 50% are recovering from addiction themselves. No instrument currently exists to measure exposure to vicarious trauma, and existing scales only measure biproducts of the exposure, such as symptoms. It is therefore difficult to assess prevalence of vicarious trauma exposure among SUPs and other “helping professionals” and the sources of this exposure. As a result, it is challenging to identify where to intervene to protect this workforce. The goal of this study is to develop the Vicarious Occupational Trauma Exposure (VOTE) Index and assess its validity and reliability in a representative national sample of SUPs. Previously-collected focus group and interview data and empirical literature on social service working conditions will be analyzed to identify vicarious trauma exposure sources. This will inform VOTE Index development, which will be modified using cognitive interview of SUPs (N=10). The refined index will be disseminated in a national sample of SUPs using quota sampling. Participants (N=600) will be recruited through partnerships with the National Association of Alcoholism and Drug Abuse Counselors and Addiction Technology Transfer Centers. A subsample will be randomly resampled to establish test-retest reliability. Respondents will be divided into training and testing datasets. Bootstrapped nonlinear principal component analysis will be used to analyze the structure of items and observations and reduce items to uncorrelated principal components. Confirmatory factor analysis will be used to assess model fit and reliability. A linear model will be fit to assess convergent and discriminant validity. The contribution of this proposed research is the development and validation of the first instrument to measure vicarious trauma exposure and differentiate it from “downstream” effects, such as symptoms and health outcomes. The VOTE Index will advance occupational epidemiologic understanding of the relationship between vicarious trauma exposure and poor worker health, workforce turnover, and client care. This index will also help researchers, practitioners, and policy-makers identify where to interv...