In 1995, when introducing a talk based on material later published as Bauer (1996) at the Free University of Amsterdam, I commented that I had been working on morphological productivity for over twenty years, but still did not feel that I had a coherent picture of the topic. In the intervening five years, I believe that I have achieved some degree of coherence in my view, and this book is an attempt to communicate that understanding. I still regard the picture presented here as provisional, and I expect it to change in the next five or ten years. Twenty-five years ago, morphological productivity was not at the forefront of linguistic theorising, but today, thanks to the dispute between connectionists and purveyors of alternative views of morphology, it has taken on a far greater importance. This not only makes it timely to provide a statement of a position, but guarantees that further research in the near future will outdate some of the comments that are made here. It is my hope that the work presented here will provide a stepping-stone in the development of a new deeper understanding – even if it is one which contradicts my own cherished positions.