“…Specifically, mixed-age groups may benefit younger children yet have no effect or even a negative effect on older children (e.g., Bailey, Burchinal, & McWilliam, 1993; Dunn, Kontos, & Potter, 1996; Winsler et al, 2002). To this point, Justice, Petscher, Schatschneider, and Mashburn (2011) recently emphasized the importance of considering a child’s reference status—that is, his or her skills in relation to those of his or her classmates—in understanding how classroom composition may be influential to children’s growth in language skills.…”