This dissertation investigates twentieth-century African American and Chicano/a novels that privilege childhood play as a site for defining the self through or against an array of social norms and dominant ideologies. Although narratives of children at play are a neglected category in literary criticism, the playing child often functions as a central literary figure for conveying the conflicted processes of self-definition for children on society's margins. In conversation with theories of play, I argue that a range of Chicano/a and African American texts predicate adult possibilities for either resistance or capitulation to conventional expectations on what transpires during childhood play. The writers in this study respond, in part, to the ideology of the early twentieth-century playground movement and its aim of instilling a sense of civic duty in the children of European immigrants. While playgrounds may have been designed to integrate certain children into U.S. society, they also excluded other children---in particular, children viewed as racial others---through segregation. Even though the children of both Mexican Americans and African Americans were not included in the play movement's goals and have continued to be excluded throughout the twentieth century, the child characters in the novels that I examine frequently contend with unsettling issues of national identity during play. Unlike the proponents of the play movement who viewed assimilation through play as a form of progress, the writers in my project often show that play is a site where capitulation to dominant values is neither progressive nor desirable for their child characters. Chapter one investigates childhood play as a key factor in determining how Chicano masculinities will be lived in relation to women, class, ethnicity, and national identity. Chapter two examines childhood play as a stage for rehearsing gender-specific adult identities that empower Chicanos but disempower Chicanas. Chapter three foregrounds childhood play as a crucial arena for working out the tensions caused by racism and sexism in relationships between African American women and girls.