International and transnational diffusion have always been an important dimension of international studies but only recently has attention shifted from the nuts and bolts of whatever it is that diffuses (technology, policies, ideas, services, values, institutions, power, people, emotions, and much more) to a more self-conscious effort to conceptualize diffusion itself. As the theme of the 2013 ISA Convention in San Francisco, a large number of panels addressed diffusion explicitly in novel and interesting ways. This symposium presents a very small subset of an intellectually impressive and multifaceted program that featured the association's diversity.