It is now illegal in France for a Muslim woman to conceal her face behind a veil when in public.
Women using a niqab or burqa to cover their faces will be liable to a fine of €150 and a citizenship course.
People forcing women to wear the veil face a much larger fine and a prison sentence of up to two years.
France is the first country in Europe to publicly ban a form of dress some Muslims regard as a religious duty, but opponents are already preparing to defy the controversial law, the BBC reports.
Authorities are preparing a poster and leaflet campaign which will stress that the French republic lives with its face uncovered.
Initially, police will move cautiously and issue warnings but some Muslim women are expected to openly challenge the law on Monday and there will be a march against the ban.
Some argue that it infringes on a woman's rights by telling her what she can't wear; others say that seeing someone's face is key to human beings understanding each other.