Although dynamic assessment (DA) has shown promise in fostering interlanguage pragmatic (ILP) competence, empirical comparisons of concurrent and cumulative group dynamic assessment (G-DA) remain limited, particularly regarding speech act production across proficiency levels using microgenetic analysis. This explanatory sequential mixed-methods study addresses these gaps by investigating the efficacy of concurrent and cumulative G-DA in enhancing the ILP competence of Iranian English-as-a-foreign-language (EFL) learners at pre-intermediate, intermediate, and upper-intermediate levels, focusing on requests, refusals, and compliment responses. To this end, 90 Iranian EFL learners were randomly assigned to nine groups (10 learners each): three concurrent G-DA groups (n = 30), three cumulative G-DA groups (n = 30), and three control (non-GDA) groups (n = 30), with each condition including learners from all three proficiency levels. MANOVA, one-way ANOVA, and Scheffé post-hoc tests revealed significant improvements in both G-DA groups compared to the non-GDA groups (p < 0.05). Concurrent G-DA yielded superior outcomes, particularly among pre-intermediate learners (η² = 0.48-0.58), followed by intermediate learners; gains were smaller at upper-intermediate levels, suggesting a ceiling effect. Microgenetic analyses of audio-recorded collaborative dialogues further illustrated how dialogic mediation in concurrent G-DA promoted greater pragmatic awareness and self-regulation, whereas cumulative G-DA provided more structured support suited to lower-proficiency learners. The findings highlight the importance of tailoring mediation to proficiency levels to optimize pragmatic development and offer practical implications for EFL instruction.
