The primary goal of this dissertation was to examine the predictors and outcomes associated with behavioural academic engagement in childhood. Behavioural academic engagement can be described as attention, participation, and on-task behaviour in the classroom (Fredricks, Blumenfeld, & Paris, 2004). Many factors have been found to predict behavioural engagement, such as classroom factors (e.g., teacher-child relationships, peer relationships, class climate), socio-demographic factors, and child factors (e.g., gender, anxious solitude). Although many educational outcomes are strongly inter-associated, the current dissertation examined the mediating role of academic engagement on the relation between classroom experiences and academic achievement. In addition, the moderating role of child factors was examined on the relations between classroom experiences and academic engagement. For the current study, data on N = 779 children were drawn from the National Institute of Child and Human Development (NICHD) Study of Early Child Care and Youth Development (SECCYD) data set. A series of moderated-mediation models were examined at both grade 1 and grade 3. Finally, predictors of change in engagement over time were examined. Among the results, support for the differential susceptibility hypothesis (Belsky, 1997) was found, indicating that anxious solitary children may be more reactive (both positively and negatively) to elements of the classroom environment. In addition, some gender effects were found, suggesting that anxious solitary boys may be at a particularly elevated risk for academic problems. Results are discussed in terms of their implications for future research and educational policies concerning the structure of the classroom environment.