Résumé:
This dissertation aims at investigating the problems that M1 students in Didactics and Applied Linguistics in Mostaganem University face in communicating effectively by means of writing. In addition, it tries to reveal the types of grammatical errors they make in writing.
The study conducts a practical investigation through a questionnaire. It is carried out by means of a diagnostic test that is given to thirty participants in the study. This diagnostic test involves writing a fifteen-line paragraph on one of the argumentative topics that are distributed to the participants. Since diagnostic test measures problems, weaknesses, or
strengths. After their pieces of writing are analyzed, it is noticed that the subject students of English, at the Master level, are still incapable of producing a coherently and cohesively wellwritten essay. The findings make the students aware of their mistakes to avoid them.
