Professionals in business and law, healthcare providers, educators, policymakers, consumers, and higher education practitioners value ethical reasoning skills. Because of this, we concentrated campus-wide reaccreditation efforts to help students actively engage in ER. In doing so, we re-conceptualized the ER process, implemented campus-wide ER interventions designed to be experienced by all undergraduate students, and created the ethical reasoning identification test to measure students’ ability to engage in a foundational step in the ER process. Using factor analysis, we demonstrated internal validity (...) evidence for ERIT scores. More specifically, confirmatory factor analysis provided support for a unidimensional factor structure, meaning stakeholders can report and analyze ERIT total scores. The unidimensional factor structure was replicated using two independent samples. Across all samples, ERIT scores demonstrated reliability consistent with professional standards. In addition, we collected external validity evidence for ERIT scores. The ERIT was sensitive to slight differences in ER training. That is, students experiencing a 75-min intervention performed better on the test compared to students without this experience. Overall, results suggested that our ER intervention may effectively increase students ER abilities and the ERIT demonstrated great potential for assessing foundational ethical reasoning skills. To further examine validity, researchers should consider known groups analyses with varying “doses” of the ER intervention, as well as measurement invariance studies. (shrink)