US president George Bush is due to meet the Queen at the White House and host a white-tie state banquet in her honour.
The monarch and the Duke of Edinburgh flew into the American capital for a two-day stay - the finale of their East Coast trip to the other side of the Atlantic.
They will be officially welcomed by Mr Bush and his wife Laura on the lawn of the White House in front of 7,000 guests, from members of Congress to Oval Office staff.
The Queen will deliver a keynote speech before heading to a garden party at the British ambassador's residence with Hollywood A-listers expected to be among the 750 guests.
In the evening, Mr Bush will don his white tie and tails for the state dinner as he and the First Lady pull out all the stops to entertain the royals.
It will be the first white-tie affair of the Bush administration.
White House aides have apparently described the dinner in the Queen's honour as the social event of the entire Bush presidency.
George Bush's father, George Bush Snr, branded it "the hottest ticket in town".
Mr Bush apparently likes to be in bed by 10pm, but the entertainment will stretch well into the evening.
Vice president Dick Cheney, secretary of state Condoleezza Rice, defence secretary Robert Gates and General Peter Pace, chairman of the joint chiefs of staff, will be among the select 134 guests.
