The thesis analyses the history of the Strategic Defense Initiative (SDI), or "Star Wars". It shows how theories about the dynamics of the arms race can be applied to SDI; and how strategic, political, industrial and other factors have interacted to shape the development of SDI. After outlining the history of Ballistic Missile Defense (BMD), the thesis describes how SDI was established in the l98Os. It assesses how far political, industrial and bureaucratic interest groups wielded influence over the relevant advisory panels and committees. It also examines the interest groups themselves, the distribution of contracts and the extent of lobbying. The thesis explores the underlying causes of SDI and its links to the wider US military space programme and anti-satellite (ASAT) programmes. It considers SDI in terms of popular culture, marketing and domestic politics. The development of SDI is contrasted with the fate of proposals for a European Defense Initiative (EDI), or a European Anti Tactical Ballistic Missile (ATBM) programme. In its final section, the thesis highlights recurrent themes in the history of BMD and SDI, and draws conclusions about the motive causes of SDI and the applicability of the theoretical literature. Sources include Congressional hearings, documents obtained under the US Freedom of Information Act, specialist magazines, the trade press, interviews, restricted briefing papers and the Pentagon's own list of SDI contracts.