She's the royal belle of the ball!
An evening of dinner and dancing was on the cards for the royals, who are on a state visit to the US.
Prince Frederik and Princess Mary danced to Stevie Wonder's Isn't She Lovely
On Wednesday night Mary and Frederik donned their finest for the gala at the Smithsonian Arts and Industries Building in Washington.
Mary lit up the room in a strapless patterned number, which showed off her incredible figure. The mother-of-four completed her evening look with diamond drop earrings and had her hair twisted into an elegant up-do.
Frederik made her dapper dance partner in a navy tuxedo and bow tie.
The Crown Princess looked beautiful in a figure-hugging gown
The couple were joined at the gala by businessmen, local politicians and representatives of the Danish Embassy. Frederik gave a speech and after dinner he and his wife of 12 years took to the dance floor.
The Danish royal palace posted a video of the couple dancing, arm-in-arm with Frederik taking the lead. After a few steps they were joined by their fellow party guests.
The couple are on a four-day visit to the US
The Crown Prince and Princess are on a four-day visit to Washington DC and Boston, having arrived on Tuesday. The purpose of their visit is to promote Danish businesses in the US, particularly in the food, technology, healthcare and maritime industries.
Engagements on their schedule include a visit to the Harvard Kennedy School in Boston, where Frederik will meet four Danish students who have received scholarships from the Crown Prince Frederik Fund. Meanwhile Princess Mary will visit the Boston Children's Hospital.
The couple have left their four children at home – Prince Christian, ten, Princess Isabella, nine, and five-year-old twins Prince Vincent and Princess Josephine.