The underlying premise of most urban art interventions is to challenge the functional use of urban space, and disrupt the social relationships integral to public life. They materialise as an extensive range of ephemeral constructions, spontaneous installations and assemblages, and eccentric performances that challenge a 'normative' organisation of city space. This thesis engages art intervention praxis in contemporary urban spaces. Brad Downey, Jason Eppink and the artist collective, Performance, Video, Intervention, known as PVI, reveal wide-ranging methods for appropriating and reformatting aspects of the urban environment. This includes subverting the coded language of road signage; staging an art gallery opening on a subway platform; constructing a pedestrian bridge using urban detritus; and mobilising participatory audiences in a 'tug-of-war.' Outwardly these disruptions appear to be uncomplicated improvisations. Collectively however, they bring together a range of performance, participatory, socially engaged, and relational art experiences that relate in critical and meaningful ways to their immediate surroundings. A broad art historical perspective and a theoretical framework are adopted throughout this thesis. As part of an analysis of provocative art strategy in urban space since the mid-twentieth century, works by Guy Debord, Ben Vautier, Hi Red Center, Valie Export, Adrian Piper, William Pope.L and Francis Alÿs, are considered. In addition, selected examples of poststructural theory and contemporary art philosophy are presented that evaluate the concept of otherness, along with participatory art practice. These frequently emerge through the practices of Downey, Eppink and PVI. Contemporary urban art interventions attract the attention of pedestrians, the media, law enforcement and institutional art constituencies. Nevertheless, academic response to the underlying agendas of those who create them remains limited. This thesis gives voice to these heterogeneous art practices, exploring the layers of complexity that comprise urban art intervention, the multifaceted outcomes and finally, the ways they can incite alternative experiences of the city.