The paper studies the language of the Cancionero de Baena, that dates back to the period of transition between Medieval and Classical Spanish. The author focusses on the use of latinisms (like ab iniçio [= ab initio], crudele, in neutro, maristela [= Ave maris Stella], ançila [= ancilla] and benine) and other lexical features, taking into account the role of the metrical structures and the pragmatic intention of the texts.