This article examines a multidimensional conceptualization of engagement and how it is related to achievement outcomes and teacher classroom practices in mathematics (including structure, support, and challenge). It draws insights from existing literature on engagement and other related research areas, including motivation and teaching effectiveness, and conducts empirical investigations using international large-scale survey and assessment data in four education systems (i.e., Singapore, Finland, Australia, and Romania) that have distinct cultural and social backgrounds and achieve at varying levels on international assessments. Confirmatory factor analysis results validate engagement as a multidimensional construct across contexts. Path analysis results reveal different patterns in the relations among engagement, achievement, and teacher classroom practices. In some contexts, relations between teacher practices and engagement or achievement vary as a function of student or teacher report. Implications and future directions are discussed.