I think it's compulsory except for HMTL (Higher Mother Tongue Language). I did some quick online research and according to the MOE website: Pupils who offer Mother Tongue Language (MTL)(i.e. Chinese/ Malay/ Tamil) or HMTL (i.e. Higher Chinese/ Higher Malay/ Higher Tamil) at the PSLE and are ranked among the top 10% of the PSLE; or are in the top 11% - 30% band who meet the language criteria (i.e. an A* grade in the MTL or at least a Merit in the HMTL) may opt to study HMTL at secondary schools. They may offer English Language and HMTL in the GCE ‘O’ Level Examination at the end of Secondary Four. And then Malay (Special Programme)[MSP] is offered to all S1 pupils from Express and Normal (Academic) courses as long as they have the interest and inclination and have not offered Higher Malay/ Malay as their MTL at PSLE. Chinese (Special Programme)[CSP] is offered to all S1 pupils from Express and Normal (Academic) courses as long as they have the interest and inclination and have not offered Higher Chinese/ Chinese as their MTL at PSLE. You can get more info about it here: https://www.moe.gov.sg/education/secondary/language-programmes#sthash.iaI2sP7b.dpuf