The relationship between the legislature and the executive in the Kingdom of Spain has been based on the principles of a parliamentary cabinet system, in which the government that is appointed by the monarch must enjoy the confidence of the representative body. Therefore, the existence of the cabinet depends on the support of a stable majority in parliament. However, it does not mean that the legislative branch dominates the government. The Spanish Constitution created the model of rationalised parliamentarism by establishing procedures that not only favour the cabinet stability, but also ensure the effective fulfilment of its functions, which are the subject of this article. Due to the complexity and multidimensionality of the issue, the article focuses on the key roles and competences of the government. Following the example of many Spanish papers on this subject, the author uses the constitutional classification of functions of the government in the Kingdom of Spain.