Disclaimer. Don't rely on these old notes in lieu of reading the literature, but they can jog your memory. As a grad student long ago, my peers and I collaborated to write and exchange summaries of political science research. I posted them to a wiki-style website. "Wikisum" is now dead but archived here. I cannot vouch for these notes' accuracy, nor can I even say who wrote them. If you have more recent summaries to add to this collection, send them my way I guess. Sorry for the ads; they cover the costs of keeping this online.
Mainwaring and Scully. 1995. Building democratic institutions: Party systems in Latin America. Stanford: Stanford University Press.
The authors wanted to find a way to compare Latin American party systems, but felt that current concepts (number of parties, ideological distance between them) was insufficient to explain the differences. So they settled on the concept of the institutionalization of party systems in Latin America. (Institutionalization means (1) stability in rules/nature of interparty competition; (2) major parties have somewhat stable roots in society; (3) major political actors view parties and electoral process as legitimate, and political elites expect that the way to government is through elections; (4) party organizations are subordinated to the interests of its leaders (these are roughly quoted).) Low levels of instituationalization (an "inchoate" party system) complicate democratic consolidation.
See notes on Moser (1999).
It's important to realize that rules aren't the only thing that matters. A lot of work on parties focuses on rules and the effective number of parties. The main message here: the number of parties isn't the only thing about parties that matters; their institutionalization matters, too.
People who study European and American party systems have focused on the number of parties; this is probably appropriate, since party systems in these areas are all institutionalized. But to understand democracy elsewhere, we must consider not only the number of parties, but also their institutionalization.
The contribution here: institutionalization can vary. We need to take account of it. There are normative qualities to parties that matter, too--not just institutions.
Research by the same authors
Research on similar subjects