The study of party systems and political parties is one of the largest subfields in political science. Classic studies in advanced democracies focused primarily on party systems and developed theories about the causes and consequences of different types of systems. In recent years, new academic work begun to differentiate parties within systems by understanding their organizational structure, their internal dynamics, the different ways in which they interact with their constituencies, and the strategies that they use to attract voters. Studies show that parties within the same system behave and react differently given their internal conditions. This article reviews three scholarly books that deal with this issue. The works analyze the internal dynamics of Latin American political parties and their capacity to respond and adapt their structures when environmental challenges take place.