Robert Michels occupies a prominent place among the founders of sociology. He belonged to the generation that followed the founding fathers of sociology. This chapter first discusses Robert Michels's life and output in the context of the political and intellectual trends of his time. It focuses on his greatest achievement, his book Political Parties. The chapter examines various dimensions of democracy that Michels touches upon and concludes with Michels's impact on scholarship. It shows that Michels's contributions to political sociology should not be reduced to the "iron law of oligarchy", and that it is essential to understand the intellectual, political, and historical contexts in which his oeuvre took shape if one is to grasp its significance. The chapter overviews the writings of later scholars who were inspired in one way or the other by Michels calls attention to additional factors that are relevant to the study of oligarchic tendencies, thereby further refining our understanding of Michels's seminal contribution.