"Whether the child is the son of a diplomat, or a shepherd-boy, they come together in the same class," says Michel Redon, the organisation's head.
Even if the parents are illegal immigrants, French law requires their children to be educated: "We are not allowed to ask about their (residence) status."
Classes are mixed in age, ability and socio-economic background. The only division is between primary-age and secondary-age pupils, and the only common factor is they don't speak French.
"The priority is French literacy: it is the first pillar of integration," M Redon says. Induction lasts from several weeks to four months. Pupils are tested in mathematical and non-verbal reasoning to ascertain ability, and placed in a classe d'accueil (reception class) at a secondary school, with specialist French as a foreign language teachers conducting their lessons.
The children join regular pupils of the school at lunch-time and breaks.
A scaled-down reception curriculum at secondary provides "not less than 100 hours" of intensive French, some mathematics and English, and introduces vocabulary that pupils will soon need in order to follow regular lessons in science and history. The emphasis is on written French.
"It is important that new arrivals start school without delay. Now, as soon as we have 24 pupils, a class is created," says M Redon.
This means classe d'accueil teachers no longer have to cope with newcomers throughout the year, with transfer from induction classes now taking place at the start of term. In Paris, there are 45 secondary reception and 65 primary reception classes, and eight special classes for those with "no previous educational experience".
After between six and nine months of reception, if pupils are judged to have enough French, they join regular classes, usually changing schools.
They are entitled to support of an extra six hours of additional French after school or at weekends.