Why are party systems less institutionalized in the Philippines and South Korea while they are more institutionalized in Japan and Taiwan? Under what circumstances or conditions do party systems become institutionalized? These two questions are the main focus of this research. This thesis explains why we see a difference in the levels of party system institutionalization across Japan, Taiwan, Philippines, and South Korea. The existing literature on party politics argue that party system institutionalization is one of the crucial components of a democratic consolidation. However, there are few cross-comparison studies exploring why party systems institutionalize differently.

Building on from Randall and Svåsand (1999, 2002) four dimensions of party system institutionalization, this study examines how changes in conditional factors bring changes to party system institutionalization across Japan, Taiwan, Philippines, and South Korea. The main argument of this thesis is that it is the variations in social cleavage, factionalism, and the way democratic transitions have occurred explains why Japan and Taiwan’s party systems are institutionalized while the Philippines and South Korea’s party systems did not.