This study aimed to design and validate the Teacher-Reported Reading Engagement Survey (TRRES) to complement self-reported measures and comprehensively assess reading engagement among adolescents. Drawing insights from literature and expert feedback, a new 10-item Likert scale instrument was created, capturing three facets of reading engagement: behavioral, social, and cognitive (Lee et al., 2021). A sample of 534 low-income 8th and 9th graders from Santiago, Chile, was used to assess TRRES's reliability for educational settings. Face validity was confirmed through expert reviews and exit interviews. Internal validity was rigorously assessed with Item Response Theory (IRT). Specifically, a polytomous Rasch model confirmed a unidimensional construct. For reliability measures, Expected A Posteriori (EAP) and Cronbach's alpha were used, resulting in very high reliability (EAP = 0.83; alpha = 0.96). To increase TRRES' practical use among teachers, a 3-item version (TRRES-A) was evaluated following criteria of being short and easy to use, yielding high reliability (EAP = 0.79; alpha = 0.87). Results highlight TRRES-A as a short, practical, and highly reliable screener for measuring reading engagement through adolescence. The initial 10-item version, suitable for qualitative purposes, complements the shorter version's practicality. Limitations include the TRRES's constrained sensitivity in distinguishing students with low levels of engagement, emphasizing the need for fine-grained analyses that yield this type of finding and inform stakeholders' decisions when choosing an instrument. Findings suggest valuable applications for educators, researchers, and policymakers seeking nuanced insights into reading engagement among adolescents.