Building upon and extending prior research, this study examines the interplay between chronological age, relational age, and perceived age-related treatment in predicting work engagement. While previous studies have often examined these three facets of age in isolation from one another, this article develops an integrative framework that combines life span theories with relational demography and age-related treatment studies. Findings from a sample of 434 school teachers from 16 schools in Italy supported the hypothesis that the three-way interaction between relational age, chronological age and age-related treatment generates asymmetrical effects on work engagement. Specifically, at high levels of perceived positive age-related treatment, relational age was positively associated with older workers’ engagement, while greater relational age was associated with reduced work engagement when older workers perceived that they were treated unfairly based on their age. In contrast, among younger workers, work engagement was positively related to perceived positive age-related treatment whatever the level of relational age.