In an attempt to engage the fundamental issues of design that are integral to our understanding of architecture and the built environment, this thesis investigates how spontaneous architecture can transcend political and social boundaries by acting as a catalyst in the urban environment. The act of catalyzing is exemplified in the informal sector through street markets and street vendors. And while the complexity of the current economic reality in the United States has resulted in a fragmented architectural typology, the dynamic articulation of marginalized vacant space in the urban core has become a strong player in a revival of localism. The underpinning goal of this thesis is to develop an understanding of the significance that these catalytic engines play in the reintegration of cities still fighting to overcome the spoils of modernity. Through a revival of localism and a re-appropriation of urban energies, markets exemplify the bottom-up approach of incremental urban design powered by formation of strong micro economies. Market case studies we visited in 6 cities in the United States: St. Louis, Missouri; Los Angeles, California; Portland, Oregon Pittsburgh, Pennsylvania; Detroit, Michigan; and New York, New York. The case studies were used as means of deriving at potential insights to the state of the American street market. An examination of prescription of catalytic opportunities – a dynamical system that has a sensitive dependence on the initial conditions of a place – presents a series of guiding principles for successful market design. / text