The objective of the subject is to show students how to approach the main macroeconomic issues in a rigorous and simple way. The discussions will focus on models that attempt to describe the behavior of the economy both in the short and long term, analyzing the effects that different economic policy measures have on different macroeconomic variables. A crucial aspect to highlight is the role that the different starting assumptions play in the conclusions of each of the models analyzed. The macroeconomics program I starts from the contents previously analyzed in Principles of Economy I and II, and then introduces successively a series of extension lines of the models contemplated there.