Rosa Corder was a painter and the mistress of Whistler’s unofficial agent, Charles Howell. It is said that Whistler observed her in Chelsea one day wearing a brown dress and passing before a black door and, struck by the color effect, used it as the basis for this portrait. Miss Corder later reported that she had posed for the picture some forty times. An acquaintance remembered her as a person of “a beautiful stillness.”
Source: The Frick Collection, Handbook of Paintings, New York: The Frick Collection in association with Scala Publishers, 2004.