Now twenty years after 9/11, this well established and uniquely composed textbook, in its revised second edition, provides a cross-disciplinary introduction to the evolving field of homeland and civil security. It unites researchers and practitioners in addressing foundational topics, risk-informed priorities, and multi-disciplinary perspectives in fostering secure societies. The book explores intellectual foundations of homeland and civil security across domains and boundaries, and how those apply to addressing real-world challenges of our time. Representing various sectors, intellectual styles, and methodological choices, the book provides a comprehensive approach within an all-hazards framework and across different levels of governance. It also demonstrates different types of writing of research and defensible analysis in different academic and professional communities. The book covers intellectual, conceptual, and policy foundations; all-hazards threat assessment; international experiences in border management; policing in the homeland security era; classical emergency management lessons of continued relevance; risk management at tribal level; risk assessment under the conditions of global connectivity; information and intelligence in homeland security; public health response to COVID-19; populism, nationalism, and violence; cybersecurity and critical web app infrastructure; leadership for homeland security; homeland and civil security cultures; ethical, legal, and social issues (ELSI); impactful research in homeland and civil security; and the scientific status of the field from the epistemic as well as the practical point of view. The book further includes a learning and research guide, a glossary, a bibliography, and an index, adding to its practical use. The book will be of distinctive worth to homeland security students in graduate courses; to an international student community taking courses in political science, public administration, security studies, and international relations; to faculty advancing in the field; as well as to researchers, analysts, and practitioners who are interested in thorough pracademic perspectives on homeland and civil security into the 21st century.