In the context of current efforts to increase student performance and to close the significant gaps in performance among student subgroups, school researchers and practitioners are paying increasing attention to schools as learning organizations. Unfortunately, the concept of the learning organization is generally vague, and school personnel have few tools available to support its assessment and to inform intervention strategies. Using data from the population of employees in 11 middle schools in North Carolina and building on an earlier analysis, this study examines the reliability and validity of a new assessment tool for assessing schools as learning organizations: the School Success Profile Learning Organization. The results align with the conceptual model that informed the development of the measure, including support for the two hypothesized learning organization components: actions and sentiments. Implications for practice are discussed in the context of evidence-based practice.