Constance McMillen, Lt. Dan Choi and Judy Shepard will share grand marshaling responsibilities in Sunday's New York City gay pride parade.

McMillen is the eighteen-year-old lesbian student who sued her Mississippi school district after officials canceled the annual prom dance rather than allow her to attend with her girlfriend.

“I'll never get my senior year back,” she told USA Today. “But the experiences that I have had because of this have really made it a lot easier. It really helped me.”

One of those experiences came Tuesday when she was invited to a gay pride reception at the White House hosted by President Barack Obama.

McMilen said she was “really honored and touched” to be asked to take part in the parade.

Lt. Dan Choi has become the leading voice of opposition to the military's “Don't Ask, Don't Tell” policy that bans gay service members from revealing their sexuality. An estimated 13,000 gay and lesbian troops have been fired under the 1993 law.

Choi twice protested the policy by chaining himself to the White House gate. Park police cut down the West Point graduate and arrested him after he refused to step down.

Judy Shepard went from small-town mother to gay activist after her twenty-one-year-old son Matthew Shepard was viciously murdered in 1998 by two men he met in a gay bar. The University of Wyoming student was beaten and left to die shackled to a post along a rural road near Laramie.

She spent much of the last decade lobbying for the Matthew Shepard & James Byrd Jr. Hate Prevention Act that adds disability, gender and sexual orientation to the list of federal hate crime protections. Obama signed the bill into law last October.

With passage of the bill, Shepard has evolved from the single issue of fighting against gay hate to a full-time gay rights activist.

“As parents of gay children we see what society has done to us and to them,” Shepard told NPR host Neal Conan. “We somehow, either intentionally or unintentionally perhaps, indoctrinate everyone to think that being gay is wrong. It isn't wrong, it's just who you are. It's the way you were born. Nothing about that makes our gay, lesbian, bisexual, transgender children different than any other children, except who they love. And at the end of the day, does that really matter to anybody? It's their life, it's who they are. And to try and convince them that they are wrong only damages them irreparably. And suicide is often the tragic result of that.”

A half-million people are expected Sunday as New York City's parade steps off at 36th Street and Fifth Avenue to wend its way to the Stonewall Inn, site of the June 1969 riots that sparked the modern gay rights movement.