The article compares the impacts of two instructional methods— Presentation-Practice-Production and task-based language teaching—to understand if there are any differences between the two in terms of improving students’ productivity skills. Seventy-eight students at Van Lang University, Ho Chi Minh City, Vietnam participated in the study. Students in the control group were trained using the Presentation-Practice-Production method, while those in the experimental group were trained using the task-based instruction method. Data was collected pre-test and post-test in response to the three research questions. The findings indicated that the task-based instruction model had a great impact on students’ grammatical performance in both writing and speaking, but was not superior to the Presentation-Practice-Production model. New research results confirmed the effectiveness of both methods when teachers put significant effort into their instructional activities.