Islamist parties and movements in Arab countries have gained great political importance by making the strategic choice to participate in the legal political process and to acknowledge the legitimacy of the existing constitutional framework. Their political participation has given rise to two major concerns both in the Arab world and in the West. First, are these parties and movements truly committed to democracy? And, will participation itself strengthen their commitment to democratic norms and procedures? The experience of participating Islamist parties and movements in Morocco, Algeria, Egypt, Jordan, Bahrain, and Yemen, as well as the armed parties in Lebanon and Palestine, reveals a complex picture.