Party Organization and the Political Success of the Communist Successor Parties * John T. Ishiyama, Truman State University Objective. Although there has been much recent work done on party systems in the postcommunist world, there has been very little systematic comparative work that examines the relationship between the organizational development of political parties and political performance. The objective of this article is to empirically ex- amine the relationship between party organization and the political success of 17 communist successor parties from 1993 to 2000. Methods. I propose a way of measuring party organizations based upon the degree of personnel overlap between the organs of the extraparliamentary party and the party in public office and the organizational density of political parties and relate these characteristics to the po- litical success enjoyed by the communist successor parties. Results. In general, I find that the more the successor party was dominated by officeholders and less reliant on a mass membership for political support in the years immediately following the transition, the more successful the party was later. Conclusions. The interaction of party organization with the party’s competitive environment was a better predictor of success than declines in the socioeconomic condition of the population, rises in popular “nostalgia” for the past, or openings created by political institutions. Democratization and the emergence of party politics in the countries of the postcommunist world have offered a unique opportunity to test some long-held propositions in comparative politics regarding the relationship between party organization and political success. Although a large amount of work has emerged on the evolution of party systems and on political atti- tudes in the postcommunist world, there has been very little systematic comparative work done on the relationship between the organizational de- velopment of political parties and political performance. To be sure, some works have appeared that investigate party organization in Eastern Europe, but these tend to focus on what causes particular party organizations to emerge in postcommunist politics rather than on party organization as a predictor of political success (Lewis, 1996; Kopecký, 1995; Kitschelt, 1995; Roper, 1995). Other works, which have examined the effects of party or- *Direct all correspondence to John T. Ishiyama, Truman State University, Division of Social Science, 207b McClain Hall, Kirksville, MO 63501 <jishiyam@truman.edu> All data and codings are available for purposes of replication. The author would like to acknowledge the helpful comments provided by Marijke Breuning and the anonymous reviewers of this manuscript. SOCIAL SCIENCE QUARTERLY, Volume 82, Number 4, December 2001 ©2001 by the Southwestern Social Science Association