Purpose: We systematically reviewed the empirical literature that reports research in the specific context of teaching EFL to identify what is known about the efficacy of using flipped learning to teach EFL, the robustness of this evidence, and to explicate the strengths and weaknesses of the pedagogy in teaching EFL. Design/methodology/approach: Adapting the systematic literature review method and combining it with content analysis of qualitative findings we narrowed our search to 40 articles that were primary studies. Findings and originality: The majority of authors examined student perceptions of their learning; one third investigated the use of flipped learning on the acquisition and development of EFL knowledge, skills and abilities. That students like learning in a flipped learning environment is the strongest finding emerging; many linking it to the facilitation of self regulated learning behaviors. However, research evidence for flipped learning's contribution to important educational outcomes is not robust and this remains a problem for understanding where or how to target the impact or value of this pedagogy. Nonetheless, other encouraging findings include that using flipped learning to teach EFL was linked to its capacity to improve idiomatic knowledge, oral and writing performance, motivation, and higher order thinking skills. Future research should focus on improving research design and reporting for flipped learning interventions, and focus on investigating key EFL learning skills particularly reading which is comparatively understudied despite its importance to language acquisition. Value: The results clarify for educators that flipped learning's capacity to influence the acquisition of key learning skills remains largely unproven.