The Indian Ocean has experienced a process of profound change in its political and strategic map since World War II. This began with the British withdrawal from East of Suez, and was followed by the entry of the superpowers into the Indian Ocean, the growth of superpower naval rivalry, and the proliferation of security problems of the states in the region. The essence of these developments is the transformation of the Indian Ocean from the stability of one-power domination to the instability of superpower rivalry. The thesis examines the process of this transformation and the Sri Lankan response from a historical perspective. The transformation of the power structure in the Indian Ocean was essentially an outcome of the changes in power configurations in world politics. The growth of superpower rivalry in the Indian Ocean must be understood in relation to the evolution of political, economic, and strategic interests of the superpowers, advances in weapons systems and naval technology, and political developments in the region. The superpower naval rivalry has three interrelated elements, viz, naval deployments, weapons deals, and jockeying for bases/logistic support in the region. It evolves in three phases: from 1968 to the 1973 oil crisis; from the oil crisis to 1978; and since 1978. There are definite linkages between superpower naval rivalry and the conflict patterns in the region. The states in the region count on the superpowers for their security because of the inherent weaknessess of the ruling elites in the region, the limits of their security options, and economic dependence. The invariable outcome is a chain reaction resulting in military pacts, puppet governments, political supression, and proxy war, which forms the texture of the international politics of the Indian Ocean region. Sri Lankan responses to superpower naval rivalry can be explained in relation to the geo-political framework of her strategic thinking, and her internal political and economic processes. In the period 1948-56, Sri Lanka identified herself with the British defence structure in the Indian Ocean. With the changes introduced by the M.E.P. regime, non-alignment became the foreign policy approach of Sri Lanka after 1956. In accordance with the growth of superpower naval presence, Sri Lanka became more sensitive to Indian Ocean strategic issues in the 1960s. After 1970, Sri Lankan policy towards the Indian Ocean took a more coherent form and was designed to balance two considerations - first, at the sub-regional level, how to deal with India; and at the Indian Ocean level, how to check superpower naval rivalry and the increasing militarization of the Indian Ocean. This was reflected in Sri Lanka's proposal for an Indian Ocean Peace Zone (IOPZ). After 1977, under the changed internal and international situation, Sri Lanka soft-pedalled her earlier more articulated position regarding superpower naval riavlry in the Indian Ocean. / Arts, Faculty of / History, Department of / Graduate