The purpose of this article is to focus on the acquisition of the text’s textual cohesion by studying the use of punctuation marks and connectives in narratives written by children at the beginning of sixth grade. It yields a dialogue between the three interdisciplinary fields of linguistics, psychology and didactics. The functions of punctuation marks and connectives are first specified, at the both linguistic and psychological levels; then we will present a study of students entering the 6th grade level. On the basis of cohesion analysis, we show that the students’ abilities in writing are much diversified. This diversification attests cognitive difficulties in writing acquisition still remaining at the beginning of grade six, that should be taken into account by teachers in planning their curriculum.