This study examines Indonesia’s use of informal diplomacy between 1985-1998, to further its interests for peace and stability in Southeast Asia. This study argues that the adoption of informal diplomacy was in response to the structural limitation of ASEAN, the nature of the problems of regional conflicts and disputes, and the Indonesian Foreign Ministry’s desire to increase its leverage in foreign policy making and implementation within the Indonesian political system which promoted inter-elites competition. At the same time, internal dynamics within the Ministry from the late-1960s - internal consolidation and the development of a new cadre of trained diplomats - made the adoption of informal diplomacy possible. This study develops an analytical framework derived from the principles articulated by various scholars and practitioners of Track Two diplomacy and on the conception of bureaucratic politics. The main purpose of this study is to outline and analyse the adoption and application of informal diplomacy in Indonesia’s diplomatic activities from the mid-1980s onward, and also to test a number of hypotheses derived from the literature on informal diplomacy. This study examines three cases where Indonesia used informal diplomacy as part of the overall diplomatic initiatives: in dealing with conflicts in Cambodia and in the southernpart of the Philippines, and in seeking to prevent armed conflicts revolving around territorial disputes in the South China Sea. The assessment of research materials and interviews during the fieldwork show that in the Indonesian context adherence to informal diplomacy principles was subject to the circumstances during the meetings, time pressures, and the availability of resources as well as the notion of bureaucratic politics. Overall, the interest of President Soeharto in the informal diplomacy process increased the status of the diplomatic endeavours, an important feature of conflict resolution approaches within the Asian setting. This study makes extensive use of documents filed in Indonesia’s Ministry of Foreign Affairs and insights from interviews with theorists and practitioners at the time.