Most, if not all (may be forgetting something), international schools offer Mandarin to some extent. Could be quite minimal to quite extensive (like SIS, CIS, ISF, KCIS, etc.). Cantonese is taught at local schools. There are English Medium of Instruction (EMI) local schools and I am pretty sure they'll do Cantonese there as well (as there will be quite a lot of Cantonese speakers anyway). Advantages is that the local system is quite cheap (cost are close to nothing) while international schools can be quite expensive. I don't know anything about applying for local (or EMI) schools, how hard it is, etc. There are many very popular local schools too. However, international school places are also very very hard to find. The schooling situation is far from ideal in Hong Kong and many people, especially newcomers, struggle to find places for their children. The more flexible you are in terms of schools the better (the most popular ones are ESF, HKIS, FIS, GSIS, CDNIS, SIS, ISF, CIS, etc.). There are other (international) options, especially in the New Territories. Whatever you decide, don't put all your eggs in one basket, because you may be empty handed. Especially lower Primary is very hard. HTH.