The cases of Hezbollah and Hamas illustrate a regional trend that features the use of asymmetric warfare by sub-state actors against a conventional army of overwhelming military power. Through rapidly expanding armouries and fighting capacities these Arab actors have recently succeeded in nudging the strategic balance in the Arab-Israeli conflict arena off balance. As a result, mounting tensions between Israel and its neighbours have drawn increased attention from scholars and practitioners who seek formulae for containing or eliminating these insurgencies. What is known about Hezbollah and Hamas? What are the accepted positions and where are the lacunae in the state of our knowledge about these organizations? After reviewing information about which there is little debate on the origins, structures, ideologies and practices of each organization, we then present the major points of disagreement concerning their intent and the questions that remain unanswered about the two organizations. Finally we outline what we see to be the challenges that lie ahead for Hezbollah and Hamas. As Hezbollah preceded the development of Hamas and in several ways has served as the model to emulate for the Palestinian group, we begin with the Lebanese organization.