The purpose of this study was twofold. Firstly, it explored Iranian EFL (English as a foreign language) teachers' receptive and productive metalinguistic knowledge as a function of educational contexts including language institutes and high schools. Secondly, the study delved into EFL teachers' perceptions of metalinguistic knowledge development in the contexts in question. A total of 200 Iranian EFL teachers participated in a metalinguistic knowledge test entailing 2 modules of production and reception. Besides, a series of semi-structured interviews were conducted with 40 EFL teachers to explore their perceptions concerning metalinguistic knowledge development. The results revealed that the high school teachers surpassed the language institute teachers regarding their productive and receptive metalinguistic knowledge. The results also indicated that the EFL teachers in both high schools and language institutes were better in receptive than productive metalinguistic knowledge. Further, the results of semi-structured interviews substantiated those of the MLK test and revealed considerable points about the metalinguistic knowledge development in the educational contexts under study. The study findings offered clear implications for stakeholders, EFL teachers, and teacher educators.