This book is based on the lectures and contributions from the NATO Advanced Study Institute on 'Nanotechnological Advances in Environmental, Cyber, and CBRN Security,' held in Sozopol, Bulgaria, in September 2024. It provides a comprehensive overview of the field, incorporating articles that address the preparation and characterization of various nanoscale materials, including metals, oxides, glasses, polymers, and carbon-based materials. Additionally, the book includes contributions on the applications of these materials in diverse security and safety-related fields. The book adopts an interdisciplinary approach, drawing on the expertise of authors from physics, chemistry, engineering, materials science, and biology. A notable feature is its representation of expert knowledge from over 15 countries, offering both comprehensive papers that provide foundational insights into specific topics and concise contributions that emphasize particular applications in various security domains.