There has been a push in recent years for students with disabilities to be educated alongside their typically developing peers, a practice called inclusion. In this study, we sought to determine whether peer effects operate within early-childhood special-education (ECSE) classrooms in which preschoolers with disabilities are educated alongside typical peers. Peer effects specific to language growth were assessed for 670 preschoolers (mean age = 52 months) in 83 ECSE classrooms; 55% of the children had disabilities. We found that the average language skills of classmates, as assessed in the fall of the year, significantly predicted children's language skills in the spring (after controlling for their relative skill level in the fall); in addition, there was a significant interactive effect of disability status (i.e., the presence or absence of a disability) and peers' language skills. Peer effects were the least consequential for children without disabilities whose classmates had relatively strong language skills, and the most consequential for children with disabilities whose classmates had relatively poor language skills. (author abstract)