This article seeks to contribute to the study of presidentialism from the standpoint of the constitution of cabinets and their operation in coalition governments. The article also provides a dynamic vision on approaches to informal institutions based on politics in Chile. Through a comparative analysis of governments since 1990, it becomes clear that the designation of cabinet members comes from a complex interaction between the presidential authority, formal political organizations, and informal mechanisms. All three blocks are influenced by common histories and complicities that expresses themselves, in an ambivalent form, in the strengthening and deterioration of political parties and political alliances. At the same time, the relationship between presidents and their cabinets has had an impact on the political base of the irrespective administrations, either strengthening or weakening them.