Dynamic assessment (DA) is based on Vygotsky’s (1978) sociocultural theory and his Zone of Proximal Development (ZPD). ZPD is the range of abilities bordered by the learner’s assisted and independent performances. Previous studies showed promising results for DA in tutoring settings. However, they did not use proficiency-based rubrics to measure students’ progress and did not mention the method of using DA practically in classrooms. The literature showed that task-based language instruction (TBLI) is effective in adult classrooms. This study combined DA with TBLI to answer four questions. What is the change in the structural control of Arabic speaking based on DA/TBLI instruction? How do Oral Proficiency Interview (OPI) without DA assistance and OPI with DA assistance compare relative to the evaluation of Arabic speaking? How do the experiences and perceptions of DA/TBLI instruction compare between teacher-researcher and OPI testers? What are the student perceptions of the DA process?