As a tool for self-evaluation and also self-regulation, rubrics can be very useful in equipping the language teachers with an assessment device. Moreover, teachers need feedback for their professional development, but how feedback is provided is a challenging question. This study was an attempt to find the effectiveness of self-evaluation through rubrics on setting up group work activities by EFL teachers as compared with the effect of supervisors’ evaluation in this regard. Additionally, EFL teachers’ attitudes with respect to the efficacy of rubrics in setting up group work activities were examined. To this end, 10 female EFL teachers with 2 years of experience were selected and further divided into two groups. One group used rubrics for setting up group work activities and the other used post-observation feedback. Their performances were video recorded and rated by two raters. The results of statistical analysis indicated that the group of teachers who used rubrics to set up group work activities and evaluate their performance significantly outperformed the group of teachers who received post-observation feedback. Teachers’ responses to the attitude questionnaire also showed that overall teachers held a positive attitude towards the use of rubrics to self-evaluate their own performance.