Book excerpt: Social Informatics: Past, Present and Future is a collection of twelve papers that provides a state-of-the-art review of 21st century social informatics. Two papers review the history of social informatics, and show that its intellectual roots can be found in the late 1970s and early ’80s and that it emerged in several different locations around the world before it coalesced in the US in the mid-1990s. The evolution of social informatics is described under four periods: foundational work, development and expansion, a robust period of coherence, and a period of diversification that continues today. Five papers provide a view of the breadth and depth of contemporary social informatics, demonstrating the diversity of theoretical and methodological approaches that can be used. A further five papers explore the future of social informatics and offer provocative and disparate visions of its trajectory, ranging from arguments for a new philosophical grounding for social informatics, to calls for a social informatics based on practice thinking and materiality. This book presents a view of SI that emphasizes the core relationship among people, ICT and organizational and social life from a perspective that integrates aspects of social theory and demonstrates clearly that social informatics has never been a more necessary research endeavor than it is now.