For the first time in the history of the Architecture Biennale the American Pavilion earned special recognition in 2012 for Spontaneous Interventions. The exhibition portrays an emerging phenomenon where citizen-led movements address urban problems with small-scale, low cost interventions. Sometimes sanctioned, sometimes not, the concept behind this movement has become known as tactical urbanism. This report examines the rise of tactical urbanism as an opportunity for the field of urban planning and describes how tactics can fit into the formal planning process. Currently, there exists a lack of understanding and research on the concept. This report contributes to the limited research by analyzing existing theory which discusses and supports the concept of tactical urbanism. After providing a theoretical foundation, four interventions displayed at the Biennale are reviewed to demonstrate the potential of this emerging approach. By evaluating the theoretical support behind tactical urbanism, the lacunae in planning literature, and the potential of this emerging approach as demonstrated by the four case studies, this report attempts to legitimize the discussion on tactical urbanism and identify how this emerging approach can fit into the formal planning process. / text