This thesis is a practice led enquiry into Locative Media (LM) which argues that this emergent art practice has played an influential role in the shaping of locative technologies in their progression from new to everyday technologies. The research traces LM to its origins at the Karosta workshops, reviews the stated objectives of early practitioners and the ambitions of early projects, establishing it as a coherent art movement located within established traditions of technological art and of situated art practice. Based on a prescient analysis of the potential for ubiquitous networked location-awareness, LM developed an ambitious program aimed at repositioning emergent locative technologies as tools which enhance and augment space rather than surveil and control. Drawing on Krzysztof Ziarek's treatment of avant-garde art and technology in "The Force of Art", theories of technology drawn from Science and Technology Studies (STS) and software studies, the thesis builds an argument for the agency of Locative Media. LM is positioned as an interface layer which in connecting the user to the underlying functionality of locative technologies offers alternative interpretations, introduces new usage modes, and ultimately shifts the understanding and meaning of the technology. Building on the Situationist concept of the constructed situation, with reference to an ongoing body of practice, an experimental practice-based framework for LM art is advanced which accounts for its agency and, it is proposed, preserves this agency in a rapidly developing field. The thesis demonstrates that the user centric practices developed by LM exert far reaching influence on the application of location-aware technologies, which sees them emerge into the everyday different to what they might have been. LM art projects are seen to have foreshadowed key categories of current location-aware applications and services. This, it is argued, is not co-incidental but is rather the result of an intentional desire, and accompanying actions, to shift the meaning of these technologies. As location-aware technologies become ubiquitous it is advanced that the forms they take and the ways in which they are employed are co-constructed by LM art practice.