This book about responsible and evidence-based decision making is written for those interested in improving the decisions that affect people's lives. It describes how to define policy research questions so that evidence can be applied to them, how to find and synthesize existing evidence, how to generate new evidence if needed, how to make acceptable recommendations that can solve policy problems without negative side effects, and how to describe evidence and recommendations in a manner that changes minds. Policies are not just the decisions made by a country's rulers or elected officials; policies are also set by corporate executives, managers of department stores, and project leaders in non-profit organizations pursuing environmental protection. The authors' suggestion are based on the fundamental belief that evidence-based decision making is superior to decisions based purely on opinion, intuition, and emotion. Because much has happened since 1984 when the first edition was published, this is a substantially different book with a new co-author, new and updated examples, new chapters, and new frameworks for understanding.