The paradigm of forms of address in Modern Spanish is subject to dialectal variation. Many Latin American varieties of Spanish, i.e. Costa Rican, Argentinean, Chilean, among others, display a tripartite system of second person pronouns comprised of "tú," "usted" and "vos." The case of Colombian Spanish is particularly interesting because there is greater variation in the patterns of use of pronominal address. The use of more than one pronoun to address the same interlocutor in the same discourse is what I will call "mixed-use." The purpose of this study is to examine the sociolinguistic variables that determine the use of "vos," "tú," "usted," and the "mixed-use" in two varieties of Colombian Spanish (Medellin and Cali). Data for the analysis were collected by means of three instruments consisting of a sociodemographic and a written questionnaires and oral interviews. Participants in the study were 293 college students from private and state universities, who were born or lived most of their lives in Medellin or Cali and surrounding areas. Results indicate that although the main extralinguistic factors conditioning pronoun choice are the same in both varieties, the outcome presents some differences. Furthermore, there are some indications of a possible linguistic change in progress in the pronominal address system of these varieties of Colombian Spanish as indicated by the variability in the use of the pronouns and the higher use of "tú" by women, younger individuals, and lower classes. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]