This article describes the development and psychometric properties of the Secondary Traumatic Stress Informed Organizational Assessment (STSI-OA), a 40-item instrument designed to evaluate the degree to which an organization is STS-informed and able to respond to the impact of secondary traumatic stress in the workplace. A sample of 629 respondents representing multiple systems of care, job roles, and functions completed the STSI-OA. Analyses revealed a 5 factor structure that explained a large proportion of variance, excellent internal consistency, good test–retest reliability, and concurrent criterion validity with the Trauma System Readiness Tool Vicarious Trauma domain. Quartile scores and means were calculated to allow for comparisons. Based on the results of this analysis, it appears the STSI-OA total and domain scores can be used to create a blueprint for organizational learning, and to reliably track progress toward desired change over time.