1. Introduction
Understanding factors that promote young children's school competence is important, given that early academic and behavioral adjustment sets the stage for later academic and social competence (La Paro & Pianta, 2000). This is particularly true for children who come from low-income households and are thought to be at risk for difficulties in adjusting to formal schooling (McWayne, Cheung, Green Wright, & Hahs-Vaughn, 2012). Engagement with peers can be influential in several domains (emotional, cognitive, social) that are important for school competence (Rubin, Bukowski, & Parker, 2006). For example, children who enter kindergarten with social skills that have been honed through many experiences with peers may transition to kindergarten with fewer difficulties than children who are less socially mature and have not had as many experiences with peers (Ladd & Price, 1987). In the present study, we observed children's peer play over 1 year in Head Start classrooms and examined how individual differences in peer play trajectories (i.e., individuals’ within-person change over time) predicted school competence a year later at the end of kindergarten.