This Handbook on Science and Public Policy will capture a landscape in flux: the relation between science and society has been changing in the last decades, and it has become a hot topic in the science system and in science policy studies. Even though historically the topic is not new, it seems that the roles of science and innovation are being debated more explicitly: the demand for science-based innovation is growing while the legitimation of scientific research is being questioned. Scientific knowledge is hailed as a significant societal and economic resource in global competition. Innovations emerging from science are considered to be the key to market success and prosperity. At the same time, scientific knowledge and research-based innovation are supposed to address so-called grand societal challenges and help achieve ‘sustainable development goals’ (United Nations 2015). Yet, there is also pressure to legitimise the increasing amounts of public funding for research worldwide. And the questions ‘how does society benefit from science?’ and ‘which research is “relevant” and “useful”?’ are raised emphatically. The changing relationship between science and society significantly challenges science policy: research is expected to foster and support innovation not only via new technologies but also in a way which is socially acceptable and sustainable. Moreover, it is expected to develop new instruments, methods and practices for its own accountability and legitimation that are accepted by the scientific community. This is where this Handbook comes in. It focuses on how science policy has changed over the last decades and raises several overarching questions: What are the consequences of changing science policies for science and the science systems nationally and internationally? How far do they go? Do they tackle the fundamental principles of science, its norms, standards and reputation systems? And what does this mean for modern science (and technology)? The chapters of the Handbook provide different answers from a broad range of theoretical and conceptual perspectives.