In what ways does the institutional structure of an Islamic political movement affect its political trajectory? This paper attempts to answer this question by comparing Islamic movements oriented towards proselytization with other Islamic movements oriented towards political representation and interest aggregation. The paper, through a comparative analysis of Islamic movements in Turkey, Egypt and Tunisia, argues that those Islamic movements that prioritize proselytization over political representation differ from other Islamic movements with respect to their ideological flexibility and adaptability to democratic principles. The data is collected through interviews and analysis of official documents of the movements.