The Spanish system of address pronouns suffered a
dramatic increase in complexity between the 15th and 17th centuries.
This study aims to explain how and why this change (or set of
changes) took place when and where it did by using the model of
koineization as a heuristic device. It argues that sociocultural
factors (particularly widespread social status anxiety) and the
salience of address forms played a primary role in driving the
changes forward. It also argues, however, that sociodemographic
factors associated with koineization (demographic movement and
dialect mixing) contributed significantly to the timing, rapidity,
location, and specific outcomes, including the grammaticalization of
vuestra merced to usted and
numerous other reduced forms.