The Obama family went to the inaugural festivities with US first lady Michelle Obama leading a co-ordinated fashion parade in a navy-silk, chequered coat and dress by New York-based designer Thom Browne.
The rest of her inauguration day outfit included a belt from J Crew, necklace by Cathy Waterman and cardigan by Reed Krakoff, whose ensemble she also wore to Sunday's swearing-in ceremony.
US president Barack Obama wore a blue tie with a white shirt, dark suit and overcoat.
Malia Obama wore a plum-coloured J Crew coat with the hemline of an electric-blue dress peeking out and a burgundy scarf, and her younger sister, Sasha, wore a Kate Spade coat and dress in a similar purple shade.
Matching colours
Mother and daughter playfully colour co-ordinated themselves - Michelle Obama's dark blue coat was matched by Malia's gloves, while Malia's plum coat echoed her mother's plum gloves.
"It is an honour that Sasha Obama chose to wear Kate Spade," said the company's creative director, Deborah Lloyd.
"She epitomises the youthful optimism and colourful spirit of the brand. We are so proud to have been a part of this historic moment."
Jenna Lyons, creative director of J Crew, said it was "a huge point of pride for all of us" to be a part of the day - as the brand was in 2009, when the girls wore outfits by CrewCuts, its children's label.
"It's amazing to see the evolution of the family. I love the way Michelle looks. She looks beautiful in something so clean and tailored. It's such an elegant choice," Lyons said, "and they all look so sophisticated. You can see how the girls have grown up in the four years, and they're still so alive and vibrant, but more sophisticated."
Mrs Obama has worn Browne's designs for other occasions, including a grey dress with black lace overlay to one of the presidential debates last autumn, and she honoured him last summer at the Smithsonian's Cooper-Hewitt National Design Awards for his contribution to fashion.
Browne made his name in modern - very modern - menswear, but he launched womenswear in 2011. He was in Paris, having just finished previews of his autumnl men's collection.
Simon Collins, dean of the school of fashion at Parsons, the New School for Design, in New York, said the Obamas showed pride in their appearance.
"They are a stylish couple and their children look fabulous . . . They show it's good to dress up, take pride in how you look." - (AP)