This study examines “spatial interventions”: street art, guerrilla gardening, public space invasions, and other unauthorized practices of place-based, site-specific art or activism that challenge the normative uses or meanings of particular urban spaces. In recent years, a growing number of individuals have taken up these forms of site-specific direct action. Some argue that they represent new strategies of political expression, even “resistance”; others, that it is little more than vandalism or pointless juvenile acting out. Yet my research suggests that many of these actions are rather connected by something more subtle, a simple willingness to reimagine the built environment on one's own terms through creative, unauthorized urban design contributions. In other words, do-it-yourself urban design.