This paper examines two differences between the party systems of the advanced industrial democracies and party systems of less developed countries, particularly in terms of the level of institutionalization. The overarching argument is that the party systems of less developed countries are less institutionalized. More specifically, we first show that most democracies and semi-democracies in less developed countries have much higher electoral volatility and less electoral stability than the advanced industrial democracies. Second, much of the literature on parties and party systems assumes the context of institutionalized party systems with strong party roots in society and further presupposes that programmatic or ideological linkages are at the root of the stable linkages between voters and parties. In the party systems of most democracies and semi-democracies in less developed countries, programmatic or ideological linkages between voters and parties are weaker. In this direction also, linkages between voters and candidates are more personalistic in democracies and semi-democracies of less developed countries than in the advanced industrial democracies.