This study analyzes the impact of a practical teaching of critical thinking on the writing skills of French language learners in an institutional context in Iran. Learners were divided into two groups, an experimental group and a control group; Honey's (2005) Critical Thinking Questionnaire was administered to the participants and their scores were analyzed to ensure that there was no significant difference between the two groups regarding their critical thinking abilities at the beginning of the training. Learners completed five semesters of coursework with identical course objectives and activities. However, the experimental group also received critical thinking training through media analysis, debates, and problem-solving activities. The analysis of the data, which consisted of qualitative analysis of students' writings in the middle and at the end of the training, indicates that the experimental group outperformed the control group in writing. These results imply that critical thinking activities had a positive impact on learners' writing skills since they allowed them to perform writing tasks by paying attention to the writing as a process, rather than only focusing on the final product.