By the interwar years, Parisian parks—artificial pockets of nature in the densely built city—had become a locus of debates around “child-friendly play spaces.” The diversity of Paris’s young population in age, gender, and social status meant that the criteria of what constituted “child-friendly” was constantly in flux and that definitions of childhood remained fluid. Interwar Parisian parks became spaces of debate over proper forms of outdoor play and the risks children faced while playing. Municipal administrators and elected municipal councilors, together with pedagogues and parents, mutually constructed the spaces of parks and park-use policies. Children’s presence in public acted both as an incentive and a challenge in creating municipal policies to regulate public spaces or in reconfiguring the organization of these spaces. Municipal council debates, parents’ petitions or complaints, reports filed by neighborhood representatives, and daily logs recorded by park guards all reveal how children’s actions in green spaces played a pivotal role in the making and remaking of the urban environment.