Leonard Weiss is an affiliated scholar at Stanford University’s Center for International Security and Cooperation (CISAC). He is also a national advisory board member of the Center for Arms control and Non-Proliferation in Washington, DC. He began his professional career as a PhD researcher in mathematical system theory at the Research Institute for Advanced Studies in Baltimore. This was followed by tenured professorships in applied mathematics and electrical engineering at Brown University and the University of Maryland. During this period he published widely in the applied mathematics literature. In 1976 he received a Congressional Science Fellowship that resulted in a career change. For more than two decades he worked for Senator John Glenn as the staff director of both the Senate Subcommittee on Energy and Nuclear Proliferation and the Committee on Governmental Affairs. He was the chief architect of the Nuclear Nonproliferation Act of 1978 and legislation that created the Defense Nuclear Facilities Safety Board. In addition, he led notable investigations of the nuclear programs of India and Pakistan. Since retiring from the Senate staff in 1999, he has published numerous articles on nonproliferation issues for the Bulletin of Atomic Scientists, Arms Control Today, and the Nonproliferation Review. His current research interests include an assessment of the impact on the nonproliferation regime of nuclear trade with non-signers of the Nuclear Nonproliferation Treaty, and more generally the relationship of energy security concerns with nonproliferation.