This chapter investigates how, in Iran, Islam constitutes an obligatory universal reference and an element of distinction at the same time. Despite restrictions, political competition over elections and the distribution of resources is real. But, ‘where’ does such competition take place? What shape does organised politics have in Iran? How does Islam and the structuration of political competition in political parties/factions interact? While parties do not exist as such, political preferences and interests regroup within factions. Instead of a derogatory term, faction (faksiun) indicates the coming together of like-minded individuals who share similar interests and mobilise to acquire elected positions as well as to orientate the policy-making process through a variety of means, ranging from alliance building to influencing public opinion. The chapter surveys the often-complex relationship between Islam and political parties in Iran.