This is the most up-to-date and comprehensive anaysis of the organization of the major political parties of France, Spain, Italy, and Greece. Conceived and framed with a common theoretical approach, four national teams of researchers followed a structural approach to the study of party organization, and they have underlined the various characteristics of the parties. The party analyses are not limited, however, to the usual measures of party organization—number of members, local branches, elected officials—or to their formal rules. Rather, the chapters highlight the power relationships among the various actors, leaders, and factions. This major work will be invaluable to all researchers and scholars dealing with contemporary European politics and party systems.