A common avenue to enable adoption of technologies and practices by small-scale producers is by means of farmer clusters. These are achieved by building networks and partnerships between farmers and other actors within the supply chain. This paper examines the role that farmer clusters play in the adoption of practices and technologies by shrimp farmers in Vietnam. Understanding the decisions that lead to adoption is important because these have a key impact on sustainable land use in aquaculture. We report on two complementary studies that test the role of farmer clusters in accessing different sources of knowledge and the trust associated with each of the knowledge sources. First, a survey (N = 193) tested the relationship between cluster membership and adoption, and showed that shrimp farmers who are members of farmer clusters are more likely to adopt three types of pond management practices (i.e. water quality management, feed input, and disease control practices). Furthermore, frequency of interaction with, and trust related to, key stakeholder actors could partly explain this relationship. Second, focus group discussions further zoomed into the dynamics that underlie the adoption of technologies and practices by cluster farmers and non-cluster farmers, respectively. We found that input retailers, buyers and hatcheries were only valued for their input on specific products and issues, but not trusted, as the information always needed being verified through testing by, amongst others, neighbors. Consequently, trust relations with these actors can be described as strongly calculative. Farmer clusters increase trust and tighten relationships between members. As a result, members trust each other when verifying information or sharing knowledge acquired from less trusted sources. On the basis of these results, we argue that reliance on existing farmer networks (i.e. clusters) is a viable tool to improve adoption of sustainable technologies and achieve land use planning objectives. Further implications for research and policy are discussed.