This paper describes the main features of the two normative models that have been in force in the Mexican legal order since this country achieved its independence, namely: legalism and constitutiona- lism. Whereas the first one emerges side by side with the Mexican Constitutions of the Nineteen Century, and has its most recent roots in the 1917 Constitution, the second one is still in a developing stage, having its clearest background in the constitutional amend- ments of June 2011.