A NATO Advanced Research Workshop that took place in Zagreb, Croatia in November 2008, brought together scientists and other experts to discuss the role of independent scientists in assessing threats from nuclear, chemical, biological and radiological weapons. This introductory chapter summarises the discussions that took place in the workshop, which addressed a range of related issues, examined current practices and their limitations, and worked through a number of case studies. Areas in which interactions could be strengthened are identified, and a number of suggestions for possible ways forward are made.