Academic engagement plays a crucial role in students' learning and performance. One of the most popular measures for assessing this construct is the Utrecht Work Engagement Scale for Students (UWES-S), which is based on a tridimensional conceptualization consisting of dedication, vigor, and absorption. However, prior research on its factor structure has yielded inconsistent results, and the substantial correlations between dimensions raise doubts about their empirical distinctiveness. Thus, questions remain whether academic engagement is experienced as a global construct, or as its three components. The present study addressed this issue by examining the dimensionality of both UWES-S17 and UWES-S9 using a comprehensive factor-analytic framework. One- to four-factor CFA and ESEM models, along with corresponding bifactor-CFA and bifactor-ESEM models, were tested using data from 453 Ecuadorian university students. The results indicated that ESEM yielded superior fit indices and less correlated factors compared to CFA. However, discriminant validity test did not support the distinctiveness of UWES-S factors, and bifactor analyses consistently demonstrated a strong general factor and weak or collapsed specific factors. These findings were remarkably consistent across both UWES-S versions. Collectively, the results suggest that academic engagement, as currently operationalized by the UWES-S, can be considered as a unidimensional rather than a multidimensional construct. Implications for conceptualization, measurement, and research on academic engagement are discussed.