Girl in Costume features a young woman of Chinese Caribbean descent. She is seated on a wooden chair, wearing a red-and-white costume. The painting style reflects the modernist influence on the artist, Sybil Atteck, as well as her interest in issues related to the diaspora and ethnic identification. 

This artwork was made when Atteck had just finished her university degree and was employed at her first art teacher's job at St. Joseph's Convent in San Fernando in South Trinidad. The painting is an example of her first artworks produced in Trinidad after receiving her fine arts degree in 1948 from Washington University in St. Louis, USA. Atteck’s oeuvre evolved throughout her career, with her most well-known works being considered expressionist and post-expressionist. The motifs in her painting practice often refer to her native land and the anthropological study of her country, its people, traditions and culture.