The exigencies of the global society of forming
not only bilingual but biliterate citizens is part of the educational current challenges (Galindo, Loaiza and Botero, 2013), especially in tertiary
education. In this sense, the argumentation
written in L1 and L2 is a required competence in
future professionals, and especially those who are
formed as foreign language teachers. This article
presents the results of a rhetorical contrastive
within-subject analysis of argumentative
texts (petitionary letters) written in English
and in Spanish by fourth-semester students
in a Colombian modern languages program.
From the perspective of the textual linguistics
(Van Dijk, 1978), the study demonstrated a
series of weaknesses in the textual structure
dimensions (superstructure, macrostructure
and microstructure) of the petitionary letters
written in English and in Spanish, confirming
with it the force of the hypothesis of linguistic
interdependence of Cummins (1983)