The present study aimed to investigate the effectiveness of Project-based learning (PjBL) in the Iranian context in an English-Persian translation class. Therefore, a project-based translation treatment was implemented to a course on advanced translation in a class of 21 students at a university in Iran. The study qualitatively investigated how students' attitudes toward the treatment differed before and after the treatment and how PjBL was practically implemented. The improvement of students' critical thinking, their attitudes toward their teamwork performance, and their translation quality were quantitatively examined. The data regarding the students' attitudes were obtained through focus group interviews before and after the treatment as well as participant observations and audio-recordings. The improvement of the students' critical thinking abilities, their attitudes toward their teamwork performance, and their translation quality were examined through a pre- and post-treatment model. The findings of the study indicated that the students' attitudes toward the treatment were generally positive, not only before but also after the treatment, although certain challenges of applying PjBL in the Iranian context were observed. Empirical evidence indicated an improvement of the students' translation quality, some of their critical thinking abilities as well as a few of their teamwork skills.