This study is focused on a group of social practices that I call "Do-it-Yourself Urban Design" interventions – unauthorized yet functional and civic-minded physical alterations to the urban streetscape in order to "improve" it. Examples include homemade traffic signs and public benches, bike lanes and crosswalks, repurposed land and infrastructure, even large development or policy proposals, all created in public space, in forms inspired by official infrastructure, without permission. Using data from 99 in-depth interviews as well as participant observation, photography, and background research on these projects and their contexts in 17 cities, the study asks who the individuals are who create these informal improvements, under what conditions they choose to do so, and why. In so doing, it demonstrates the way that symptoms of uneven planning and development processes are experienced and responded to in everyday life.

I argue that the creative transgression of DIY urban design holds great potential, both as an instance of critical awareness of the inequities and failing of urban policy and a form of active, participatory citizenship in local placemaking. Yet the privileging characteristics of typical do-it-yourself urban designers, the cultural values represented in the projects they create, and the nature of the relationship between DIY efforts and professional planning also reveal the stubborn persistence of prejudice and inequality in social practice and the design of public space. Their seemingly laudable spirit of altruistic self-reliance can also mean elite individualism and a further discounting of the accountability and democratic oversight of local government. In these ways, DIY urban design ironically mirrors many of the problems with the official planning and development environment that its creators ostensibly aim to address. Practitioners and policymakers alike must enjoin more equitable participation and legitimacy in DIY efforts if they are to realize their promise of more responsively, democratically, and creatively designed urban spaces.