Many studies have established that there are important life-long benefits of attending pre-K. At the same time, recent research suggests that pre-K attenders may enter and exit kindergarten exhibiting less optimal social and learning behaviours than their non-attending peers, and little attention has been paid to what factors may contribute to these patterns of development after children enter kindergarten. The current study will address these gaps in knowledge using nationally representative data from the Early Childhood Longitudinal Study Kindergarten Class of 2011 to examine the social and learning behaviours of pre-K attenders and nonattenders at kindergarten entry and exit. Moreover, we will determine the extent to which children's social and behavioural skills change at differential rates across the kindergarten year as a function of pre-K attendance and their kindergarten classroom experiences, with a focus on the academic rigour, activity settings and teacher-student relationships. (author abstract)