This article shares outcomes from a year-long participatory planning process – one that brought together children and youth engagement, city planning, campus planning, and a university environmental design course to explore child-friendly, dense and affordable housing for a city of approximately 100,000 residents. This process of engagement asked design students to include youth participation and child-friendly cities as an integrated component of sustainable cities. The article shows varying degrees of transformation, views of children as credible participants, and values gained from the project. Many undergraduates changed their thinking about the role of young people in design processes and outcomes.