A growing body of research shows that in diverse societies and cultures, daily contact with nature is an important element of people’s health and well-being. However, because parks are not equitably distributed throughout cities, some urban residents do not have access to these resources and related benefits. Given limited budgets for park acquisition and maintenance, many cities wonder how to provide more equitable access to nature for all citizens. One approach is to naturalise school grounds and open them to surrounding communities after school hours. This chapter explores how green school grounds can be conceived and used as neighbourhood parks, how city parks can serve as outdoor classrooms, and how these spaces can be designed to serve intergenerational needs through participatory processes with schoolchildren and older residents. To illustrate these ideas, we present a case study of participatory design in Boulder, Colorado (USA). Drawing on interviews with key agents in this process, we share lessons and recommendations that might be applied to other places where local governments or schools seek to increase community access to green spaces.