101.fStudents at universities confront several problems during their learning process, be they pedagogical or material. One example is overcrowded classes. Students in this situation face many obstacles with learning different subjects especially writing. Students at Constantine University 1 are no exception. They face many difficulties because of the large number of students who are found in a single class; these students are always uncomfortable and find it hard to give writing the attention it deserves. The current work is an attempt to shed light on the effects of overcrowded classes on both teachers and students while dealing with the writing skill. Accordingly, it is hypothesized that over-populated classes affect negatively teachers’ and students’ performances when it comes to the teaching and learning of the writing skill. The current research work aims basically at exploring the nature and types of these consequences. The targeted sample includes second-year students and ‘written expression’ teachers at the department of English, Constantine University 1, during the academic year 2013-2014. Data collection is made through two questionnaires. The first one was designed for teachers; the second was given to second-year students. Findings have shown that overcrowded classes during written expression courses affect badly both teachers and students particularly in terms of motivation, class management and delivery of feedback which are the backbone of any successful writing instruction.