Buku ini membahas bagaimana masyarakat membentuk kompetisi politik yang demokratis, dengan fokus pada jumlah partai politik.
Isi buku ini:
1. Introduction; 2. Social heterogeneity and the number of parties: a theory; 3. Describing social heterogeneity: measures and testable hypotheses; 4. Social heterogeneity and party system fragmentation: empirical evidence across space and time; 5. Israel: new parties for new groups?; 6. Israel: testing hypotheses about sectarian party success; 7. The United States: new parties for new groups? testing hypotheses; 8. Conclusion: party system fragmentation and beyond.