This book comprises 25 contributions focussed on nanotechnology for sensor applications. They stem from presentations at the NATO Advanced Research Workshop "Nanomaterials for Security". The chapters cover a broad but interrelated range of topics, including nanophysics, nanotechnology, nanomaterials, sensors, biosensor security systems, and explosive detection. They reflect many significant advances over the past two years as well as some entirely new directions of research that are just beginning to be explored.