Party System Institutionalization in Democracies

Party systems vary in many dimensions. Variation in the stability and predictability of the party system in democratic elections is captured by the concept of Party System Institutionalization (PSI). Where the party system is stable and predictable, it is institutionalized. Where it is in flux and major new contenders regularly appear, the party system lacks institutionalization. Fundamental differences among party systems revolve around the level of institutionalization. Institutionalized systems make governing easier, lower the probability of populists winning office, promote greater economic growth, and are associated with better public policy. Many scholars who work on Latin America, the post-Soviet region, Africa, and Asia have employed the concept “party system institutionalize” to analyze these regions. Because party systems do not develop in a linear way, in some cases this means the study of deinstitutionalization. When deinstitutionalization happens abruptly, it is called party system collapse or party collapse. The article focuses on PSI, erosion, and collapse in democratic regimes; a different literature analyzes party institutionalization under authoritarian regimes.