This paper outlines the factors that affected the development of a knowledge based decision support system (KBDSS) during a period of rapid industry change. The development process was led by a steering committee consisting of farmers, extension officers and milk processor representatives. The committee requested that changes be made to the KBDSS as a response to different circumstances in the Australian dairy industry due to the deregulation of the milk market. These changes were implemented using the services of a software development, marketing and product placement company. The research indicates that the use of the recommended approaches to the development of a KBDSS did not work well in the rapidly changing environment and that the interpretation that is necessary to determine the effect of deregulation on farmers added conflict and complexity to the development process. Moreover, it was found that approaches such as prototyping and stakeholder involvement that are advocated in situations involving requirements uncertainty do not necessarily provide an adequate solution.