This report explores the question of how populist parties organize and towhat extent they have intrinsic characteristics and are alike in their organization. As this problematique is under-researched there is an important gapin our understanding and knowledge concerning populism and its parties. Largely a synthetic work, the report seeks to fill this void in existing researchthrough an overview of the secondary literature and an inventory ofscattered evidence covering a set of political parties broadly labelled populist. The evidence reveals that these parties in a range of European countrieshave experienced remarkably similar organizational attributes andstyle. A clear pattern has emerged. In a broad comparative perspective,three identifiable patterns are particularly notable as regards the organizationof these parties. The first pattern is centralized organizational structures. The second pattern, and linked to the former, is personalized leadership,which is often but not always based on charismatic authority. Thethird pattern is factionalism or intra-party division.