Over the years a multitude of Information Systems development methodologies have emerged. While many of these methodologies have shown promise, prior research has shown that system development is a highly circumstantial process, and that no one methodology will be optimal for every context of every project. Research has also shown that system development practitioners have been using an ad hoc approach to modify formal methodologies in order to create a better fit for their circumstances. This paper presents a more formal approach. A new model is described, based on the principles of general systems theory, which can be used to adapt existing information system development methodologies through the identification of general isomorphic properties. The results are reported from an experiment that was conducted to measure the model in terms of developer satisfaction with the finished product, the development process, and the problem solving process. Also, the results of an evaluation by expert judges on finished products created using the model are shown. These results show that there is promise in the new model and that more research needs to be conducted.