Britain will vote on whether to remain in the EU on Thursday 23 June, Prime Minister David Cameron has said.
The prime minister made his historic announcement in Downing Street after briefing the cabinet.
He said he would be campaigning to remain in a reformed EU – and described the vote as one of the biggest decisions “in our lifetimes”.
Ministers immediately divided up into the leave and remain camps as the campaigns got under way in earnest.
Home Secretary Theresa May heads the list of those who have announced they will campaign to stay – but Justice Secretary Michael Gove has signed up to the leave campaign.
Leave campaigners are also hoping London Mayor Boris Johnson will join their cause – but he has yet to declare where he stands.