Since the dawn of automobility, cars and children’s play have made for an uneasy combination. Their strict separation reflects wider binaries within modernist planning. Play streets subverted the modernist ideal, allowing for the coexistence of cars and children, and sparked much debate around safety, urban space allocation, and the role of mothers. Emerging in Copenhagen in the 1930s as an alternative to playgrounds in poor and densely populated neighbourhoods, play streets in the post-war period were transformed into an element of traffic integration, absorbed into modernist planners’ schemes of citywide differentiation. This article spotlights the ambiguities within this, drawing on Danish newspaper articles, archive sources, and City Council debates to trace discussions around play streets, their role in the eyes of various stakeholders–from mothers to (predominantly male) urban planners, from police officers to landlords–and their (meagre) implementation during the period 1930–1970. It shows how, despite efforts to provide children with dedicated places for play, they often preferred spaces not purposefully designed for them, such as the street, with many stakeholders acknowledging this fact. Struggling to reconcile cars and children’s play, play streets appeared as a pragmatic approach, which later became increasingly contested.