This chapter is about radical innovation and disruptive technological change. Discovering the nature and mechanisms of disruptive technological change can help to understand the long-run dynamics of innovation and map profound transformation in socio-economic systems. The chapter considers four concepts essential for the understanding radical and disruptive technological change: long waves, techno-economic paradigms, general purpose technologies (GPTs), and disruptive technologies. We conclude with some insights on the emerging technologies in the latest techno-economic paradigm. The tools and concepts given here remain the cornerstone of a useful theory of innovation and change even in our current complex socio-technical landscape.