The study of Discourse Markers explores the interdiscipline crossroad zone by excellence in where Grammar and Pragmatic interacts. In this framework, in this paper is propose a grammar and pragmatic description of the spanish discourse marker por un lado… por otro. The examples, that exhaust the more significant possibilities of use of this discourse marker, have been extracted of a Corpus of 60,000 journalistic articles of diverse genre. In the grammar characterization of the discourse marker are described the prototypical forms and the variants of contextual adaptation that it more habitually adopts por un lado… por otro in relation to the diverse grammar functions that can carry out. Por un lado… por otro is a discourse marker with a discontinuous structure in the textual space that makes cohesion from diverse textual fragments by means of logical interrelations. The marker orders in a symmetrical way a semantically homogenous space, indicating that the two discursive sequences, although sometimes in a contrastive way, take part of the same commentary. In its pragmatic characterization is analyzed the computational information of processing that contributes por un lado… por otro to discourse. The pragmatic function of discourse markers has an interactive nature and its consists of guiding the interpretative trajectory of the textual users. Discourse markers works, first, as an ostensive stimulus (that is to say, like a element of focalization used in a deliberate way by the producer by take the control of attention of the receiver) that, secondly, they guide the process of discursive interpretation, taking influence in a positive way in the minimization of the processing effort that makes the receiver. [ABSTRACT FROM AUTHOR]