Task-based language teaching (TBLT) is one of the contemporary approaches which attracts a vast amount of research in the past decades. Research on the dissemination of TBLT, however, has provided abundant evidence of hindering factors in various educational contexts, especially in Asian cultures. Two major groups of factors were reported. One is directly associated with the teachers, namely their language proficiency, understanding of TBLT, and beliefs about language pedagogy. The other group involves the social, cultural, and educational forces which indirectly militate against the teachers' implementation, including assessment policy, large mixed-ability classes, social accountability, and instructional time constraint. This situation reflects an existing gap between what second language acquisition research has to say and classroom realities, in which the teacher plays a crucial bridging role. The current paper draws on studies on TBLT published within two to three recent decades to argue that teachers' belief is a key mediator of their practice which interacts with their classroom experiences and contextual factors. Based on this position, the paper attempts to depict a conceptual framework that captures the interaction to provide implications for future research and work on EFL teachers' education and development.