The major purpose of the present study was to uncover if the structural complexity of type I and type II conditionals can greatly be mitigated by applying the sandwich format of dynamic assessment (DA). More specifically, this study aimed at investigating the contributory role of DA in improving intermediate EFL learners’ acquisition of conditional structures. To this end, a quasi-experimental pretest- posttest design was utilized. From the target population of students studying English at one of language institutes in Isfahan, two intact classes were selected based on a convenient sampling method. The age of the participants was between 19 and 24. Subsequently, they were randomly assigned to two equal groups receiving their instruction through the present, practice, produce (PPP) method, and the treatment group members were exposed to the sandwich format of DA. The findings revealed that the students in the experimental group significantly outperformed those in the control group on the immediate and delayed post-test. The results indicated that interaction, mediation, and feedback were important factors helping EFL students overcome the challenging task of learning conditionals. Notably, the findings may have important implications for EFL, learners, teachers, and materials developers.
