While the available research literature appears to support the implementation of task-based language teaching (TBLT) in Western countries, few studies have been conducted to investigate its impact on classroom practice in Asia, especially in comparison with the presentation-practice-production (PPP) approach which many Asian teachers still favour. The current study explores the differential effects of the PPP approach and a task-based approach on Vietnamese students’ writing performance and self-regulation while writing descriptive and argumentative paragraphs. The study involved 138 students of English Language Studies at a university in Vietnam. Results show that both approaches are effective in enhancing students’ text quality. The students in the PPP condition had significantly higher scores on linguistic accuracy in the immediate posttest than the students in the TBLT condition. Conversely, students in the TBLT groups had significantly higher scores on lexical diversity in the immediate posttest than the students in the PPP condition. With regard to self-regulation, the students in the TBLT condition had significantly higher scores on the immediate posttest than the students in the PPP condition .