Decision making about environmental sustainability is complex, involving both factual and value-based judgements by farmers. Some of the factors involved in making these decisions, such as the financial implications and riskiness, the urgency of the problem, ease of implementation and trialling and compatibility have been addressed elsewhere. The current paper discusses a number of less-explored issues involved in this type of decision making, including the need for multiple sources of knowledge such as farmers’ values and goals, an understanding of social and demographic issues, and consideration of the catchment or landscape context in which farmers live. It highlights scientific knowledge as only one of these knowledge sources, with other sources also needed in complex decision making. Evidence from a Western Australian case study suggests that there has been a shift in farmers’ values over the past few decades and that there is now a greater responsiveness to management solutions which include environmental considerations, even among the 40% of farmers driven primarily by monetary goals. Changing social conditions, particularly the roles of women on farms and of off-farm income, suggest greater potential for the incorporation of environmental considerations into farm management. However, demographic issues, particularly issues such as limited employment opportunities, the declining provision of services in areas dominated by an agricultural economy, and the trend of increasing privatisation of extension services, suggest that there remains potential for greater environmental exploitation in some areas. The role of scientists in helping farmers to address environmental sustainability is discussed, with an acknowledgment that there are insufficient scientists with the required skills available. Scientists need to work in teams with local people to develop a sufficient depth of understanding to translate abstract research findings into solutions that are relevant at the farm level. Highly participatory approaches (which empower farmers rather merely inform them) can help scientists to understand farmers’ needs and motivations, but involve losing control of highly focused research agendas. Environmental Management Systems are one way in which scientific research and group learning can help empower farmers to understand and make better decisions about the environment.