Integrated assessment is a discipline that takes a holistic, problem-oriented approach to scientific assessment. It is increasingly being applied to consider a range of environmental issues, including water resource management problems. This paper considers lessons for integrated assessment arising from a project focused on water allocation options in the Namoi River catchment, Australia. It is seen how the problem focus of this work prescribes the requirements placed on the structure, components and conceptualisation of the integrated assessment model. A brief description of the model illustrates the ways in which these requirements are addressed. Lessons for integrated assessment arising from this work are then described. These relate to the importance of identifying the modeling problem and objectives, balancing disciplinary perspectives, selecting appropriate spatial and temporal scales, and development of trust with stakeholder groups.