The central concern of my research over the past two decades has been to contribute to understanding of the development of scientific knowledge. From a variety of perspectives - philosophical, historical, psychological, computational, and sociological - I have attempted to describe the nature of the discovery, development, and acceptance of scientific ideas. Historical case studies of important developments in science, such as Lavoisier’s oxygen theory and Darwin’s theory of evolution have provided material for reflection on how science grows. However, even the extensive publications and notebooks of such scientists provide a limited record of their work, and much reconstruction is required. I am now examining closely an important scientific development that has taken place very recently: the formation and discovery of the bacterial theory of ulcers.