Since the beginning of the third wave of democratization in the late 1970s, Latin American party systems have confronted several challenges, and they have frequently been transformed. There have been various types of changes. While some systems collapsed in the 1990s (e.g., Venezuela and Peru), others realigned (Colombia, Chile, and Uruguay), or expanded (Argentina and Mexico), or were able to become consolidated and ensure their stability over time (e.g., Brazil). What factors explain the transformations in party systems during the past three decades, and how can Latin American party systems be classified according to their attributes? In trying to answer these questions, scholars of Latin America have undertaken studies that are both theoretically and empirically rich. Their work has increased our knowledge of the party systems and representative democracies in the region. Different factors have been highlighted in order to explain the changes these systems have undergone since the third wave of democratization. Some works emphasize the importance of institutional reforms introduced by politicians or by constitutional assemblies. The questions they address are the following: What political reforms have been introduced into Latin American political systems, and what effects have they had on the party systems in different countries? The researchers do not limit their attention to reforms of electoral systems. For example, some of them also study decentralization processes and their effects on party systems. From a different perspective, other authors focus on changes in electoral preferences and their effects on the configuration of political power, exploring how regional economic, political, and social changes have affected voter preferences and the political configuration of party systems. Still others consider the crises of democratic representation in these countries, underlining the decline in the programmatic character of parties as an explanatory variable for the crises and noting that the level of institutionalization of a party system declines when parties abandon this distinctive feature and become clientelistic or personalistic instead. On the other hand, in order to describe party systems and to observe the changes they have undergone, academics have proposed a set of concepts and measurements that make it possible to identify their levels of institutionalization (i.e., stability vs. volatility), nationalization, and programmatic structuration, among other aspects. The operationalization of these concepts has provided researchers with useful data for describing, comparing, and analyzing the party systems of the region transversely over time. Understanding the transformation and characteristics of Latin American party systems over time sheds light on both the progress democratic regimes have made and the setbacks they have suffered within specific countries and in the region at large.