The current study aimed at examining the impact of a program based on collaborativist learning theory on developing EFL critical writing skills and interaction among second-year languages and translation students. The study adopted a quasi-experimental design. One experimental group of 33 EFL students at second-year Faculty of Languages and translation in the academic year 2020/2021 was randomly chosen to participate in the study. They received instruction through Microsoft teams in the light of a program based on collaborativist learning theory. To determine the necessary critical writing skills to be enhanced through the treatment, a checklist was designed, and the critical writing skills were approved by the jury members. Based on these skills, a critical writing test was developed and used as a pre-post test. In addition, an EFL interaction scale was designed and approved by the jury members to measure the students' level of interaction in English language classes. The t- test was used for the statistical analysis of data. Results showed that there was a statistically significant difference between the mean scores of the experimental group in the pre- and post-test in overall critical writing skills and each sub-skill, favoring the post test scores. There was also a statistically significant difference between the mean scores of the experimental group in the post-administration of the EFL interaction scale and the test value, favoring the post administration. Therefore, the collaborativist learning theory based program had a positive effect on developing EFL critical writing skills and interaction among second-year languages and translation students.