In the Spanish tradition, descriptive grammars based both factually and methodologically on a corpus gleaned from identified contemporary sources, mostly taken from literature, do not appear until the several editions (¹1831–⁸1847) of the grammar of Vicente Salvâ (1786–1849), and later in that of Andrés Bello (¹1847–1860). A small part of Salvá’s corpus does come from medieval and renaissance authors, but these are used only to illustrate diachronic change in Spanish. Salvá’s empirical and descriptive approach, and that of other 19th-century Spanish and Spanish American grammarians that follow him, leads to specialization within the wider field of grammar and, as is shown here, syntax is the area that profits the most, both in depth and in size or extension. There is no precedent for this grammaticographical tradition in the Renaissance, when a literary corpus is used only for those parts of the texts that traditionally dealt with metrics and versification. Renaissance grammarians derived the authority of their texts from the transfer of the rules of Latin grammar into Spanish, not from the language of the literary canon. During the 18th-century Enlightenment grammars based on a literary corpus begin to appear, but the authors from whose works the corpus is taken are those of a previous (non-contemporary) period. As shown in this article, it is in the 18th century that descriptivism results in an increase in the importance of syntax, although that increment in size is minor by comparison with that which takes place during the 19th century beginning with the works of Salvá.