The Program on International Politics, Economics, and Security (PIPES) is a particularly active group with strong ties to the department. Directed by Charles Lipson, PIPES meets weekly to discuss research issues in international politics. Visiting scholars present work-in-progress, as do faculty from around the University. Graduate students are central to PIPES: they present their own work, conduct study groups, and serve as discussants at most faculty presentations. The students, among the best in the social sciences, represent a broad array of research interests, from international monetary affairs to international environmental institutions, from the renegotiation of treaties to nuclear proliferation.