Markets can be regarded as institutional settings that promote innovations by mechanisms such as competition. But market dynamics as institutional transformations can be assessed under the aspect of innovation, too. In this chapter, innovation is understood as a socially perceived (technical) innovation and conceived of as an institutional development and social change. For this, the chapter presents contributions of new economic sociology. One can speak of an US-American strand of new economic sociology, which is represented mainly by the social network approach to markets of Harrison White, Brian Uzzi, Ronald Burt, and others. Also, there is a French strand of new economic sociology, mainly represented by the work of Pierre Bourdieu, convention theory (economics and sociology of conventions), and actor-network theory. These approaches can be regarded as critical counterparts to classical economics, especially to the concept of market in neoclassical economics. They focus instead on quality as a social construction and markets as social structures. The chapter will relate the concept of market to innovation (“innovation in markets”), and it conceives the establishment of markets as an institutional innovation itself (“innovation of markets”).