The task-based language teaching (TBLT) is a learner-cantered pedagogical approach which promotes learners’ engagement in communicative tasks. TBLT has been implemented widely including in Thailand where English is used as a foreign language. However, the evidence of its effectiveness remains equivocal. This review was conducted to examine and synthesize the evidence of TBLT benefits in EFL contexts. However, it was found that most TBLT research in EFL contexts aiming to draw the effects of TBLT intervention tends to be predominated by low rigorous designs. For Thailand in particular, most studies report students’ positive perceptions about the TBLT interventions while the claims to improve language competences are vaguely proved due to the low evidence-based rigor. From such review-based findings, the paper proposes a call for design-based research to evaluate the impact of TBLT on language competences and learning skills. Adopting rigorous designs which provide counterfactuals would produce a more secure evidence for policy and practices of the TBLT implementation in the Thai EFL context
