This study analyzes various perspectives of modernization theory in some Middle Eastern countries and examines the impact of modernization, both in its western and eastern formula, on the legitimacy and stability of these countries. It also examines those external factors that influenced these countries' internal and external policies. The study's major hypothesis is that Modernization + Secularization = Instability, whereas Modernization - Secularization = Stability in Middle Eastern Islamic countries. Secularization is a component of both the western and eastern paths; consequently, a Middle Eastern country that attempts to modernize and secularize along either of these paths is doomed to instability. The hypothesis suggested herein is analyzed in regard to twelve Middle Eastern countries. The principal conclusions are that the collapse of the Shah's regime in 1979 was a direct result of his western and secular policies; Egypt's political and economic instability was a result of its unsuccessful oscillation between west and east; Lebanon's limited experience with liberal democracy was a failure because of internal secularization and sectarian politics, and external interference by foreign powers; the instability of the Ba'athist regimes of Syria and Iraq is a consequence of their secular socialist policies; and South Yemen's Marxist-Leninist policies were a major cause for its unstable political regime. Even though Libya's Third International Theory of Modernization, based on an Islamic framework, seems to generate political stability for Qadhafi's regime, his latest adoption of Marxist-Leninist ideology may delegitimize his rule; on the other hand, the latest external pressures by the United States and Western European powers on Libya have legitimized Qadhafi's rule and boosted his popularity, for the time being. In contrast, Algeria's pragmatic socialism has been carefully tailored to its Islamic tradition and therefore has resulted in one of the major stable political systems in the Middle East. Contrary to the pessimist modernization theorists who predict the demise of the traditional monarchies when attempting to rapidly modernize, modernization in Kuwait, Saudi Arabia, Jordan, and Morocco seems for the most part to have been accompanied by political stability due to their exclusion of the secular component of the western path.