Throughout the history of social movements for both environmentalism and development, there has existed an associated undercurrent of practical grassroots innovation committed to values of social justice and environmentally sustainable developments. Grassroots innovation proceeds through groups and activities different from mainstream innovation processes in institutions such as universities, public research and development labs and innovation departments at companies; and which have traditionally networked around formally organized research institutions. Modern science, technology and innovation institutions have historically struggled to recognize other modes of knowledge production, including indigenous and community-based knowledge and non-codified forms of knowledge. There is always innovative activity at grassroots level operating beneath the radar of economic and scientific institutions. Those institutions conventionally set research and development agendas, and provide support and resources, and market and capitalize upon innovation in society. This chapter presents an overview of the key concepts discussed in the subsequent chapters of this book.