Controversial transmigration(external) programs have moved millions of people from the cores of domestic economies to national geographical peripheries to ostensibly facilitate a more equitable resource distribution. However, it is not well understood how transmigrants become accepted and how they position themselves within the local networks of migrant-receiving rural communities. We examine how ethnicity and transmigratory experience affect informal knowledge-sharing networks in 16 coffee and cocoa farmer groups in Lampung, Indonesia. Drawing on these social networks and key socio-economic characteristics of 315 farming group members, we examine core-periphery network structures and centrality distributions within these farming groups. We show that individuals from the majority ethnomigration group who are the descendants of Javanese(external) migrants tend to form the core of the local farmers’ knowledge networks, apparently benefiting both from strong cultural links to the central regions of the country in Java as well as strong embeddedness in local communities. Our findings also call attention to possible marginalization(external) of original members of peripheral rural communities in central government-sponsored transmigration and export-oriented agricultural extension programs.