This paper explores the relationship between stranger-kingship and contractual authority in the history of the island of Sulawesi (Indonesia). In most parts of Sulawesi, social and political stratification were always pronounced. At the same time the power of kings and chiefs was restricted by more or less explicit social contracts defining their rights and duties with respect to the political community as a whole, typically consisting of an oligarchy of local nobles. These contracts, spelled out during inauguration ceremonies and on other ritual occasions, were backed up by realistic threats of violence against the ruler, as well as by supernatural sanctions. Besides its contractual character, another characteristic feature of Sulawesi kingship was that rulers were perceived as outsiders to the community - typically by virtue of foreign and/or divine origin, sometimes perhaps also as a result of sickness or physical abnormality. Stranger-kingship enhanced the effectiveness of the social contract by making the ruler easier for his people to discipline or depose if necessary, and harder for them to envy or hate, as well as more objective and impartial in his own dealings with them. These points are illustrated using historical and anthropological data from various parts of Sulawesi, particularly the Bugis kingdoms of the southwest peninsula, the island sultanates of Buton and Banggai off the east coast, and the chiefdoms of Gorontalo and Buol in the north.