Corrective feedback (CF) as a multifaceted practice needs to be explored from different perspectives. Achieving relative consensus among language teachers and experts in a particular context on the most effective CF strategy for monolingual and bilingual language learners appears to be understudied. As such, a fuzzy TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) model was applied to accommodate varied and conflicting opinions in ranking the effect of three corrective feedback strategies including mid-focused oral metalinguistic CF, written metalinguistic CF, and oral/written metalinguistic CF. To this end, 79 monolingual Persians and 79 bilingual Turkmens aged between 13 and 18 from two language institutes in Golestan Province of Iran participated in the study comprising three experimental and one control group each. The experimental groups were provided with CF strategies on their most recurrent grammatical errors detected through pretests while the control groups received none. The results of the fuzzy TOPSIS approach ranked oral/written metalinguistic CF and oral metalinguistic CF as the best strategies for monolingual Persians and bilingual Turkmens respectively. The fuzzy TOPSIS approach provided experts with the opportunity to include their opinions on the weight of criteria and the impact of CF strategies towards enhancing the experts’ agreement on the issue. It was shown that a single CF strategy might not be appropriate for all EFL learners in different contexts. The approach also provided a framework for soliciting wider participation of the experts when conditions favor the application of multi-criteria decision-making methods, or speedier assessments are required.
