The present study explores Moroccan science teachers' perceptions of teaching science subjects through foreign languages, mainly French, in Moroccan secondary schools. Seventeen science and technology teachers have been interviewed and data were analysed following the grounded theory methodology. The researcher constructs hypotheses based on data collection and analysis following axial coding. The findings of the study reveal that although science teachers hold positive attitudes towards the change in the language of instruction, they do not agree with the way this new initiative is being implemented. According to them, neither teachers nor students have been prepared to cope with a foreign language as a medium of instruction. They think students' low French proficiency is the major challenge in this new initiative. Hence, they admit to resorting to the mother tongue to facilitate students' content learning. Also, they have expressed their dissatisfaction with the prioritization of French as a foreign language and as a language of instruction. Instead, they suggest preparing young generations to switch to English as a medium of instruction through introducing English as a first foreign language at the primary and middle schools instead of French. The study ends up with some implications to overcome the challenges of the new policy.