Research Findings: Although children's temperament contributes to their academic success, little is known regarding the mechanisms through which temperament is associated with academic achievement during the transition to elementary school. One such mechanism may be school engagement, but findings are inconsistent and limited. Across 2 waves of data at the transition to school, we examined the role of kindergarten emotional and behavioral engagement as links between preschool temperament (positive emotionality, anger, and effortful control) and kindergarten academic achievement among a predominantly Mexican/Mexican American sample of 241 children drawn from Head Start classrooms. Significant direct effects indicated that preschool anger was negatively, and positive emotionality and effortful control positively, associated with kindergarten behavioral engagement. Only preschool anger was significantly associated with kindergarten emotional engagement. In turn, kindergarten behavioral, but not emotional, engagement was directly, positively associated with kindergarten academic achievement. All 3 preschool temperament measures were indirectly related to kindergarten achievement via kindergarten behavioral engagement, and anger was indirectly related to kindergarten achievement via emotional engagement. Practice or Policy: Findings highlight the importance of understanding the role of engagement as a mechanism that can foster children's academic achievement at a key developmental transition.