In many countries, water allocation has become increasingly controversial as competition has increased. This paper summarizes a research programme of seven studies over 10 years that has developed social psychological theories of justice, equity and fairness for application to the implementation and evaluation of water allocation decisions. Much of the research has been conducted in the context of the development of government sponsored water reform in Australia. This reform has emphasized the need for integrated approaches to water management which encourage efficiency of use through markets, and environmental sustainability through the introduction of environmental (in-stream) flows. The initial study tested the adequacy of equity and procedural justice theories to provide explanations about people's evaluation of decisionmaking in the context of water allocation. They were found to provide insufficient scope for the evaluations. Therefore, the second and third studies developed alternative universal fairness principles and adopted the fairness heuristic as a concept for judging the justice of individual water allocation decisions. It was found that the public's universal fairness principles in contrasting allocation case studies were relatively stable over a decade, and provide criteria for judging allocation decisions. Water was consistently seen as a public good; the environment was seen to have rights to water; and procedural issues were important in allocation decision-making. The most recent four studies have shifted to the local or situational fairness contexts. These four studies examined the justice or fairness principles that were appropriate for decision-making when irrigation communities were faced with possible decreased allocations to provide for environmental sustainability. Three studies were survey based, and one was an action research project to develop fairnessbased rules for community management. The conclusion from these four studies was that local procedural justice issues, particularly those pertaining to public involvement for local people in decision-making, were significant determinants of judgements of the fairness of the decisions. Economic considerations had some importance, but were not the over-riding issues, and water markets were seen as unacceptable processes for water allocation or re-allocation. The research also provided evidence that self-interest is tempered by pro-social motivations such as fairness when making water-allocation decisions. Finally, it was evident that the public could make relatively complex judgements which used dimensions that go beyond the scope of traditional social psychological definitions of equity and procedural justice.