Free agent center Jason Collins revealed to Sports Illustrated last week that he is gay.
Collins' revelation was announced Monday, after he informed former teammates, friends and others the news was coming.
Collins wrote this week's cover story for the magazine after meeting with SI executive editor Jon Wertheim and contributor Franz Lidz.
The exclusive is part of a package the magazine is doing on gay athletes.
Collins opens by writing, "I'm a 34-year-old NBA center. I'm black and I'm gay."
His essay explains why he decided to come out and how his family reacted.
"I realized I needed to go public when Massachusetts congressman Joe Kennedy, my old roommate at Stanford, told me he had just marched in Boston's 2012 Gay Pride Parade," Collins wrote. "I'm seldom jealous of others, but hearing what Joe had done filled me with envy. I want to do the right thing and not hide anymore. I want to march for tolerance, acceptance and understanding. I want to take a stand and say, 'me, too.' "
Collins wrote that his family was apprehensive about him revealing his sexual orientation publicly.
"My maternal grandmother was apprehensive about my plans to come out publicly," he wrote. "She grew up in rural Louisiana and witnessed the horrors of segregation. During the civil rights movement she saw great bravery play out amid the ugliest side of humanity. She worries that I am opening myself up to prejudice and hatred. I explained to her that in a way, my coming out is preemptive. I shouldn't have to live under the threat of being outed. The announcement should be mine to make, not TMZ's."
Collins' twin brother, Jarron, told SI that he never suspected his brother was gay. The two starred together at Stanford. Others were also surprised.
"My first reaction was I felt for him," former teammate Emeka Okafor said, adding that he wasn't expecting Collins' news. "I was like, 'Wow, you've had to carry this around you for so long."
Collins also reacted to the U.S. Supreme Court's recent arguments about same-sex marriage.
"The strain of hiding my sexuality became almost unbearable in March, when the U.S. Supreme Court heard arguments for and against same-sex marriage," he wrote. "Less than three miles from my apartment, nine jurists argued about my happiness and my future. Here was my chance to be heard and I couldn't say a thing. I didn't want to answer questions and draw attention to myself. Not while I was still playing."
News of Collins' revelation comes a month after former NFL offensive lineman Kwame Harris, who also attended Stanford, spoke publicly for the first time after being outed in January.
Wertheim wrote on SI.com that Collins is the "first openly gay athlete in major team sports."
NBA commissioner David Stern reacted to Collins' revelation in a statement.
"As Adam Silver and I said to Jason, we have known the Collins family since Jason and Jarron joined the NBA in 2001 and they have been exemplary members of the NBA family," Stern said. "Jason has been a widely respected player and teammate throughout his career and we are proud he has assumed the leadership mantle on this very important issue."
Former president Bill Clinton also issued a statement about Collins, who was a college classmate of his daughter Chelsea.
"I have known Jason Collins since he was Chelsea's classmate and friend at Stanford," Clinton said. "Jason's announcement today is an important moment for professional sports and in the history of the LGBT community. It is also the straightforward statement of a good man who wants no more than what so many of us seek: to be able to be who we are; to do our work; to build families and to contribute to our communities.
"For so many members of the LGBT community, these simple goals remain elusive. I hope that everyone, particularly Jason's colleagues in the NBA, the media and his many fans extend to him their support and the respect he has earned."
Collins, who has averaged 3.6 points and 3.8 rebounds in his 12-year career, played in six games for the Washington Wizards this season.
Wizards president Ernie Grunfeld said in a statement released by the team, "We are extremely proud of Jason and support his decision to live his life proudly and openly. He has been a leader on and off the court and an outstanding teammate throughout his NBA career. Those qualities will continue to serve him both as a player and as a positive role model for others of all sexual orientation."
He has also played for the New Jersey Nets, Memphis Grizzlies, Minnesota Timberwolves, Atlanta Hawks and Boston Celtics.
"We have great respect for Jason and his message today. Creating an environment where we support, respect, and accept our players' individual rights is very important to us," said Hawks managing partner and NBA governor Bruce Levenson in a statement issued by the organization. "Jason represented everything that we look for as a member of the Atlanta Hawks and we are proud he wore our jersey."
Cal coach Mike Montgomery, who was Stanford's head coach when Collins played for the Cardinal, also issued a statement: "Jason is an exceptional person who put a great deal of thought into this decision. This took a lot of courage, and I support him, along with his family and former teammates who have nothing but respect for Jason. I have known him and his family for a long time, since his sophomore year in high school when we started the recruiting process. He is a tremendous player and smart, fierce competitor. Jason is guy you want to have on your side."