We present a new model of software development by transformation. The model uses a problem solving approach to automate and document the development process. The model is incorporated in a system called Glitter, which explicitly represents the goals and methods that lead to transformation applications, and the selection criteria used to select one transformation over another. Glitter, using a partnership approach with the user, has been able to automatically generate 90 percent of the planning and transformation steps in the examples studied. Further, by using a by-product of the Glitter system — a record of the planning that leads to a final implementation — we are able to begin to look at automating other software lifecycle processes.