This book sets out to explore the generation of technological knowledge and the introduction of technological change. Cristiano Antonelli enters this new area of debate by arguing that increasing returns in the production of knowledge apply, albeit under a very specific and contextual set of complementary conditions. Increasing returns can take place within technological districts and clusters where qualified interactions among connected innovators make it possible to take advantage of the modular indivisibility and cumulativeness of technological knowledge. Antonelli illustrates his argument by reference to technological systems and complementarities, irreversibility, and collective knowledge; by examining the role of learning and technological communication as key factors in defining the rate and direction of change within technological systems; and by identifying technological districts and clusters within a theoretical framework which values local externalities, irreversibility, and endogenous structural change. "The Microeconomics of Technological Systems" proposes a general, interpretative framework which identifies, qualifies, and specifies the specific context and processes which make it possible for increasing returns to apply in the localized production of technological knowledge and change. In so doing, it builds on the results of systematic explorations of the microdynamics of technological knowledge and change over a large number of European technological districts and clusters centred on new communication and mechanical engineering technologies.