ABSTRACT Children’s playgrounds became part of the urban planning and evolution of Western cities at the turn of 19th and early 20th centuries. The overall objective was to improve urban children’s well-being and enhance safety by channelling play activities away from city streets towards designated play spaces. This article zooms in on the process of creating recommendations, norms and standards related to playgrounds. The subject under scrutiny is the standardization of childhood in Finland during the 1960s and 1970s, a period characterized by the most intense phases of urbanization, the establishment of welfare state institutions and the evolution of legislation pertaining to children's play spaces as well as vigorous discussions concerning children's environments. These planning discussions, norms and standards have had far-reaching consequences. They are not only prominently evident in today's Finnish cities but have also significantly influenced our contemporary perception of children's place within urban contexts. This study brings a social history approach to the academic discussion of the role of standardization in urban planning. Simultaneously, it examines the development of the increasingly standardized urban childhood in Finland in the 1960s and 1970s and asks what kind of childhood this standardization aimed to promote.