Because most public preschool programs are means tested, children enrolled in these programs accordingly have peers from predominantly low-income families who present lower cognitive skills and more behavioral problems, on average. The present study examined the role of having a higher percentage of peers from higher-SES families on gains in children's receptive vocabulary and executive function skills at the end of prekindergarten. Participants included 417 children attending a prekindergarten program that is not means tested. Findings indicated that having a higher percentage of peers from higher-SES families showed small, positive associations with greater gains in end-of-prekindergarten receptive vocabulary and executive function skills. Results are discussed in the context of current proposals to increase access to publicly funded preschool for higher-income families. (author abstract)