Rogelio V. Solis/Associated Press

Constance McMillen did not get to attend her high school prom after her Mississippi high school canceled it rather than allow her to bring her girlfriend. But she will be an honored guest at an even bigger celebration: she has been named a grand marshal of the gay pride parade in New York.

Heritage of Pride, which runs the pride parade in New York, announced her appointment, and her lawyer confirmed that Ms. McMillen would attend the parade, to be held June 27.

Ms. McMillen, a senior at Itawamba Agricultural High School in Fulton, Miss. who has been out as a lesbian since eighth grade, had planned to take her girlfriend to the prom but was told by the school that she could go alone or with a male date but not with a female date.

After the American Civil Liberties Union sued the school district on her behalf, the district canceled the prom. School officials then said that parents would organize a private event with school chaperones that Ms. McMillen could attend, and she did, along with a handful of other students. But many more students went to another prom the same night at a country club to which Ms. McMillen said she was not invited.

Ms. McMillen also plans to attend a promlike celebration May 1 in San Francisco held by the National Center for Lesbian Rights.