Contents -- Figures -- Tables -- Abbreviations -- Acknowledgments -- 1. Introduction -- 2. Collective Action, Institutions, and Bias in the PAC System -- 3. The Size and Scope of the PAC System -- 4. PAC Formation among Interest Groups: Incentives and Their Limits -- 5. PAC Formation among Interest Groups: Institutional Constraints -- 6. PAC's, Groups, and Public Policies -- 7. PAC's, Groups, and the Political Parties -- 8. Conclusions -- Appendixes -- A. Merged Data on Associations and PAC's: Sources, Procedures, and Descriptions -- B. Coding PAC's according to Occupational Type: Data Sources and Coding Rules -- C. Explanation of the Interactive Model of PAC Affiliation -- Notes -- Works Cited -- Index.