The young royal, 25, looked lovely as she stepped out for the New York event in the v-neck number, which features a fitted bodice and a full swing skirt.
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She was spotted wearing the dress earlier this year during a trip to Berlin with sister Princess Eugenie.
Beatrice even wore the dress with the same black patent Mary-Jane shoes, although she decided against the wide black belt that pulled her outfit together in January.
She was accompanied by her boyfriend Dave Clarke, 31, at the Charity: Water Gala event that benefits the organisation that aims to bring safe drinking water to every person on the planet.
Also at the gala was Eugenie, who was more low-key than her sister in a black dress with a lace panel. She did, however, add a splash of red lipstick.
Beatrice's outing came just days after she attended the society wedding of Zoe Stewart and Jake Warren with Cressida Bonas.