This paper aims to shed greater light on the importance of opium for the local economy of Java and intra-Asian trade in the early modern period through a close analysis of the Amphioen Sociëteit (1745-1808) (‘Opium Society’). Established in 1745, the Sociëteit was a privileged, chartered, joint-stock company, that, together with the VOC, exercised the monopoly of the import and retail trade in opium in Java. Whilst the objectives and institutional framework of the Sociëteit are clear, little is known about how and why it contributed to the interests of autochthonous Dutch firms and entrepreneurs, as well as the mixed mercantile community of Batavia. How, for example, did the Sociëteit sustain the formation of a mercantile elite in Batavia, and the emergence of cross-cultural commercial partnerships? In analysing these questions, this paper contributes diverse insights to our understanding of the critical importance of opium to private traders engaged in intra-Asian trade during the early modern period.