•Resource users in the Great Barrier Reef trust some sources of reef-related information more than others.•For some information sources, trust is differentiated with respect to age, residential location, and stakeholder group.•Commercial fishers reported the lowest levels of trust in most information sources. Trust is an important element of social capital that is increasingly recognized as integral to effective natural resource management, yet the concept remains relatively unexplored in the environmental social sciences. In large, complex resource systems where numerous and diverse stakeholders receive information from a variety of sources, managers must make efficient use of limited financial and human resources by communicating effectively with the public and targeting engagement efforts to build trust where needed. Using Australia’s Great Barrier Reef (GBR) as a case study, we investigated to what degree stakeholders trust reef-related information from five sources: research institutions, non-government organizations (NGOs), the Great Barrier Reef Marine Park Authority (GBRMPA), industry groups, and friends, family and coworkers. Additionally, we explored whether trust is demographically differentiated among resource users (n = 2985), considering four demographic variables: age, gender, residential location (north, central, and south), and stakeholder group (tourism operators, commercial fishers, indigenous residents, and non-indigenous residents). Overall, research institutions were the most trusted source of information, followed by friends, family, and coworkers, NGOs, the GBRMPA, and industry groups. Trust did not differ with gender, and was negatively related to age for all sources of information except friends, family and coworkers. Stakeholders living in the northern GBR region were less trusting of research institutions compared to those living in the central and southern regions. Finally, for most information sources, trust was differentiated across stakeholder groups, with commercial fishers reporting the lowest levels of trust in the GBRMPA, research institutions, and non-government organizations. In demonstrating the heterogeneous nature of trust in the GBR, this study presents a necessary first step towards developing targeted strategies to build trust, improve communication, and promote stewardship in a large, complex natural resource system.