Background: Nurses, social workers, and medical residents are ethically mandated to engage in policy advocacy to promote the health and well-being of patients and increase access to care. Yet, no instrument exists to measure their level of engagement in policy advocacy. Research objective: To describe the development and validation of the Policy Advocacy Engagement Scale, designed to measure frontline healthcare professionals’ engagement in policy advocacy with respect to a broad range of issues, including patients’ ethical rights, quality of care, culturally (...) competent care, preventive care, affordability/accessibility of care, mental healthcare, and community-based care. Research design: Cross-sectional data were gathered to estimate the content and construct validity, internal consistency, and test–retest reliability of the Policy Advocacy Engagement Scale. Participants and context: In all, 97 nurses, 94 social workers, and 104 medical residents were recruited from eight acute-care hospitals in Los Angeles County. Ethical considerations: Informed consent was obtained via Qualtrics and covered purposes, risks and benefits; voluntary participation; confidentiality; and compensation. Institutional Review Board approval was obtained from the University of Southern California and all hospitals. Findings: Results supported the validity of the concept and the instrument. In confirmatory factor analysis, seven items loaded onto one component with indices indicating adequate model fit. A Pearson correlation coefficient of.36 supported the scale’s test–retest stability. Cronbach’s α of.93 indicated strong internal consistency. Discussion: The Policy Advocacy Engagement Scale demonstrated satisfactory psychometric properties in this initial test. Findings should be considered within the context of the study’s limitations, which include a low response rate and limited geographic scope. Conclusion: The Policy Advocacy Engagement Scale appears to be the first validated scale to measure frontline healthcare professionals’ engagement in policy advocacy. With it, researchers can analyze variations in professionals’ levels of policy advocacy engagement, understand what factors are associated with it, and remedy barriers that might exist to their provision of it. (shrink)