For the last two centuries, the nation state has posed a formidable challenge to multinational empires. It has served as a base for modernization, secularization, and democratization - and also for the formation of totalitarian regimes. Today, the nation state faces challenges from multiple directions. National minorities demand self-determination while religious forces seek to undermine secular governments, and global migration movements destroy the cultural uniformity once considered essential for the formation and preservation of nation states. Nationalism and Binationalism is the first book of a three-volume set which addresses key challenges facing the contemporary nation state from a global perspective, but with special emphasis on the Middle East and Israel. The book reflects research conducted under the auspices of the Israeli Democracy Institute's "Nation State Project," which analyzes Israel's complex reality in which a Jewish majority contends with an Arab minority, ultra-Orthodox religious forces reject the authority of the nation state, and an immigrant society exhibits substantial cultural and ethnic variance. This first volume examines binationalism - a topic that has gained popularity in academic circles as a possible solution to the Israel/Palestine issue - from a theoretical point of view and from a practical angle, analyzing cases in which two ethnic groups or nations share one political system and govern it jointly. The book challenges the accepted notion of national unity in several countries, such as France and Germany. Additionally, it considers the precedents of Belgium and Canada, as well as other countries, which are considered as binational. The history of the binational concept in Israel is explored and different opinions are presented on its future prospects: the idea of Israel within the borders of 1949 as a binational state, and the possibility of a binational state between the Jordan River and the Mediterranean.