Barack Obama has danced the night away after he was sworn in for his second term as US president in front of hundreds of thousands of people.
In his inauguration address he warned America it must make "hard choices" to reduce the cost of health care the the size of its financial deficit.
But later there was time to dance with his wife Michelle during the traditional night of balls that heralds the beginning of a new four-year presidential term.
The stars were out in force, and Dreamgirls star Jennifer Hudson sang for the president and first lady as they danced at the official inaugural ball. She sang Al Green's Let's Stay Together - Mr Obama crooned a few bars of the soul classic a year ago at a fundraiser at Harlem's famed Apollo Theatre.
Other stars included Stevie Wonder and Alicia Keys, who changed her hit Girl On Fire to sing "He's the president and he's on fire...Obama's on fire. Obama's on fire." The crowd joined in with We Are Young by the American band Fun.
Mrs Obama wore a custom-made Jason Wu ruby-coloured dress to the inaugural balls.
Mr Obama was officially sworn in on Sunday as required by law, but the glitter of Inauguration Day was pushed forward a day as January 20 fell on Sunday this year. It meant the grand ceremony fell on the birthday of revered civil rights leader Martin Luther King.
The president said every citizen deserved a basic measure of security and dignity, and held up healthcare and social security as that strengthen the country. And he declared that a decade of war was ending, the nation's economy was recovering and "America's possibilities are limitless".
He said: "My fellow Americans, we are made for this moment, and we will seize it, so long as we seize it together."