Party system institutionalization (PSI) is a critical dimension of modern democracies. However, conventional approaches to institutionalization do not include party systems' ability to adapt and respond to challenges that emanate from society, one of the crucial traits in Huntington's definition of institutionalization. We discuss conventional approaches to the analysis of PSI. Building upon the idea of social orders put forth by North, Wallis, and Weingast, we argue that the analysis of institutionalization at the level of party systems must consider the system's ability to provide open access and to include all sectors: that is, the system's ability to incorporate demands that emanate from society. We propose a new conceptualization and operationalization of PSI, and we present a new data set of PSI indicators for 18 Latin American countries. Finally, we analyze the data to assess the level of PSI and type of party system in each Latin American country.