First published in German in 1911, this book introduces the concept of iron law oligarchy.

Considered a classic text of social sciences, Political Parties analyzes the power structures of organizations such as political parties and trade unions.

Robert Michels argues that all organizations, even those in theory most egalitarian and most committed to democracy, such as socialist political parties, are in fact oligarchical and dominated by a small group of leadership.

Robert Michels was a German-Italian sociologist known for his contributions to elite theory through the study of political behavior in intellectual elites. He is best known for his book Political Parties.