This article deals with the emerging concept of Employee Engagement (EE) and its meaning for public administration research and theory. Generically, EE reflects a positive, fulfilling, affective-motivational, work-related state of mind characterized by vigor, dedication, and absorption. In an attempt to understand whether the concept of EE is meaningful for public administration research and theory, we examine its essence and foundation using a comparative method. First, we compare EE with two well-established employee–organization relationship (EOR) concepts: Affective Commitment (AC) and Job Involvement (JI). Second, we compare EE in public versus private sector employees, and finally, we compare the concept in employees and managers in the public sector. Our study is based on an interactive sample of 593 employees and managers from both the private and public sectors in Israel. The results support several hypotheses. First, EE is an empirically distinct construct compared with other EOR concepts. Second, EE is higher among public sector employees than private sector employees. Third, EE is higher among public managers than public employees. Implications of our findings and recommendations for future theoretical and empirical studies of EE are discussed.