This study explored the effect of metacognitive reading strategy intervention in English on helping Moroccan learners reversely transfer metacognitive reading strategies from English (L3) into French (L2). In particular, it investigated whether an improvement in metacognitive reading strategy in English (L3) would lead to an improvement in reading comprehension achievements in French (L2). 67 eleventh-grade students were purposively selected and randomly assigned to an experimental group (n = 35) and a control group (n = 32). All participants were administered the "Metacognitive Reading Strategies Questionnaire" (Abu-Rabia, S. (2019). The effect of degrees of bilingualism on metacognitive linguistic skills. "International Journal of Bilingualism, 23"(5), 1064-1086. https://bibliotheek.ehb.be:2102/10.1177/1367006918781060) and a reading comprehension pre-test and post-test in English and French. Only the experimental group received training in metacognitive reading strategies (MCRS) in English. The difference between metacognitive strategy awareness levels and reading comprehension scores before and after the intervention was examined using one-way-MANOVA. Results indicated a significant improvement in the experimental group's metacognitive strategy awareness and reading comprehension scores in both English and French. Based on these results, we suggest that learners of English as a foreign language should be explicitly trained in the use of MCRS, and a link between the different languages taught at school should be established. Thus, metacognitive reading strategies and skills acquired in one language can be positively transferred to another.