Among scholarly researchers, the Utrecht Work Engagement Scale (UWES) is a popular scale for assessing employee or work engagement. However, challenges to the scale’s validity have raised major concerns about the measurement and conceptualization of engagement as a construct. Across 4 field samples, we examined 2 measures of engagement, the UWES and the Job Engagement Scale (JES), in both factor structure and patterns of relationships with theoretically hypothesized antecedents and consequences. In a fifth field sample, we examined the construct-level relationships between engagement and related variables, while controlling for sources of measurement error (i.e., item-specific factor, scale-specific factor, random response, and transient). By examining 2 measures, each derived from different theoretical bases, we provide unique insight into the measurement and construct of engagement. Our results show that, although correlated, the JES and UWES are not interchangeable. The UWES, more so than the JES, assesses engagement with overlap from other job attitudes, requiring improvement in the measurement of engagement. We offer guidance as to when to use each measure. Furthermore, by isolating the construct versus measurement of engagement relative to burnout, commitment, stress, and psychological meaningfulness and availability, we determined (a) the engagement construct is not the same as the opposite of burnout, warranting a reevaluation of the opposite-of-burnout conceptualization of engagement; and (b) psychological meaningfulness and engagement are highly correlated and likely reciprocally related, necessitating a modification to the self-role-expression conceptualization of engagement.