Jeanne L. Reid and Sharon Lynn Kagan, The Century Foundation and PRRAC, April 2015, available here

"A formidable obstacle faced by preschool programs that seek to serve socioeconomically and racially diverse children is the prevalence of neighborhood segregation. Because many parents prefer to send their children to neighborhood programs, early education programs often reflect neighborhood housing patterns that result in high levels of segregation by income and race. Moreover, the number of high-minority, high-poverty neighborhoods is rising, with young children being the most likely age group to live in segregated neighborhoods. An analysis of 384 metropolitan areas across the country found that many children who are three to five years old reside in neighborhoods with levels of racial and economic segregation that are very high, and higher than for older children."

"Peer diversity may also offer important social benefits to all children, irrespective of their SES [socioeconomic status]. Children from a variety of socioeconomic backgrounds and race/ethnicities can learn from peers who are different, and these benefits may be enduring and profound. Usually by kindergarten, children have developed an awareness of racial/ethnic identities and social status, and the ability to make social comparisons. Exposure to peers from a variety of racial, ethnic, and socioeconomic backgrounds can inform these perceptions. We know that in racially diverse kindergartens, for example, children’s acceptance of peers and friendships may transcend racial or ethnic identities. Friendships in diverse classrooms could thus diminish the social isolation that characterizes children in socioeconomically and racially homogenous neighborhoods, whatever their predominant race or income."