In the last few decades, Communicative Language Testing (CLT) has successfully achieved a default position among language teachers, however, the number of testers who claim to employ an overtly communicative approach is very limited (Morrow, 2012). Group Dynamic Assessment (G-DA) is one of the outcomes of CLT which is believed to have the potentiality of accelerating learning L2 skills. Hence, the present quasi-experimental study examined the impact of G-DA on Iranian EFL learners’ oral production, motivation and classroom anxiety. In so doing, the validated Persian versions of Student Motivational State Questionnaire (Guilloteaux & Dörnyei, 2008), and Foreign Language Classroom Anxiety Scale (FLCAS) (Horwitz, Horwitz, & Cope, 1986) were employed. Moreover, IELTS Speaking Tests were administered as the indicator of participants’ oral proficiency level before and after receiving the treatment. First, 100 pre-intermediate and intermediate level EFL learners were selected based on convenience sampling from some accredited language institutions in Hamedan. Next, the paper-based TOEFL Junior Standard Test was given and based on test rubrics, 77 participants were chosen and were randomly put in four groups; pre-intermediate and intermediate EFL learners in experimental G-DA groups A and B, and pre-intermediate and intermediate ones in Non-DA (NDA) control groups C and D. Groups A, B, and C consisted of 19 participants, and group D consisted of 20 ones. All four groups participated in 14 speaking sessions; G-DA-based mediations were provided for groups A and B using the preplanned Poehner’s (2005) mediation typology, and groups C and D received placebo treatment. Having conducted pre-test and posttest phases, the following results were achieved; To investigate the impact of G-DA on EFL learners’ oral production, two separate Independent Samples t-tests were employed, and the results indicated a significant positive effect on both groups. Four separate paired-samples t-test
