This meta-analysis is an investigation into the impressibility of two dimensions of the speaking skill, namely accuracy and fluency, in relation to the experimented treatments among Iranian EFL undergraduates. Having surveyed a collected bank of 74 research reports, the relationships among the variables in the 14 included studies were examined. More specifically, the analysis involved a statistical review of 67 effect sizes (at 95% CI) calculated from studies conducted between 2006 and 2016, including 890 participants. The analysis indicated that in 77% of the experimented treatments, the students performed as well as the students in the regular programs with no significant improvement in oral accuracy. The analysis also demonstrated that 63% of the treatments did not yield significant improvement in oral fluency in comparison with the regular instruction. Moreover, the synthesis of the effects of the contextual factors showed that low-level (i.e., elementary) learners experienced a better improvement in speaking performance. The analysis also revealed that, among the experimented treatments, dialogic tasks were most effective on oral accuracy while interviews were influential in promoting the students’ both oral accuracy and fluency. Finally, the quality of the study reports was analyzed and some directions for further research were suggested.
