State education in Spain is almost exclusively co-educational and is entirely free, from nursery school through to university. This does not include the costs of books, stationery and excursions, which are borne by the parents.
Generally considered to be very good, the Catalan state school system should be seriously considered by any expat family. There are a few conditions to this: Unless your child is fluent in Spanish, you will need to ensure that they take some intensive language lessons. Even better is to let them learn Catalan, as almost all schools (public and private) in Barcelona teach in this language. If you have nursery-aged children this will not be so much of an issue – almost all expats report that their young children absorbed the language incredibly quickly. Additionally, as there are so many expats in Barcelona, many state schools offer language coaching to newcomers before the school year begins.
Private schools (usually Catholic) are an ´intermediate´ option both in terms of language and cost. Most lessons are conducted in Catalan, but private schools offer English as well that it is a popular choice with expats.
International schools are the most expensive choice, although they do offer all classes in English (depending on the school). Although this has helped many expat kids feel more comfortable with the move (and the schools have extraordinarily high university acceptance rates), there is a very real danger of children becoming ´ghettoised´ into an expat community and never really experiencing Barcelona.