This study evaluates the health of the U.S.-Canadian defense industrial relationship, which is critically important as the U.S. Department of Defense expands the national technology and industrial base. The CSIS study team gathered and analyzed a wide range of quantitative data and conducted interviews with government and industry officials involved with bilateral cooperation on both sides of the border. In addition to looking at top-level history, legislation, policy, and trends, the study team undertook five sectoral case studies highlighting different aspects of the benefits from and challenges facing bilateral cooperation. The study finds that the benefits to both partners exceed what either could obtain solely by relying only on its own national resources. While the overall U.S.-Canadian defense industrial relationship remains sound, the study team identifies a range of recommendations to enhance its value to both partners.