How do scientists impact society in the twenty-first century? Many scientists are increasingly interested in the impact that their research will have on the public. Scientists likewise must answer the question above when applying for funding from government agencies, particularly as part of the 'Broader Impacts' criterion of proposals to the US National Science Foundation. This book equips scientists in all disciplines to do just that, by providing an overview of the origins, history, rationale, examples, and case studies of broader impacts, primarily drawn from the author's experiences over the past five decades. Beyond including theory and evidence, it serves as a 'how to' guide for best practices for scientists. Although this book primarily uses examples from the NSF, the themes and best practices are applicable to scientists and applications around the world where funding also requires impacts and activities that benefit society.