The immediate impact of Thursday's policy change, endorsed by more than 60 percent of the organization's 1,400 voting members, is likely to vary widely.
Of the more than 100,000 Boy Scouts of America units in the U.S., 70 percent are chartered by religious institutions.
Those include liberal churches opposed to any ban on gays, but some of the largest sponsors are relatively conservative denominations that have previously supported the broad ban - notably the Roman Catholic Church, the Church of Jesus Christ of Latter-day Saints and Southern Baptist churches.
Mormon officials on Thursday night said the church would stay involved with Scouting "based on our mutual interest in helping boys and young men understand and live their duty to God and develop upright moral behavior."
Bishop Paul Loverde, the leader of the Catholic Diocese of Arlington County in Virginia, issued a statement saying the vote would likely force the diocese to reconsider sponsoring troops in about 50 of its parishes, while an official with the diocese of Washington said the new policy is not in conflict with Catholic teaching.
The Assemblies of God, a conservative evangelical Christian denomination, said the change "will lead to a mass exodus from the Boy Scout program." It also warned that the change would make the BSA vulnerable to lawsuits seeking to end the ban on gay adults.
"This has been a challenging chapter in our history," BSA Chief Executive Wayne Brock said after the vote. "While people have differing opinions on this policy, kids are better off when they're in Scouting."
The vote of the century-old group symbolizes just how quickly many Americans' views on homosexuality are changing. Just last summer the Scouts reaffirmed its desire to keep out openly gay boys and gay adult volunteers, a policy the Supreme Court upheld in 2000. But the escalating pressure from families and major donors in the past year forced the Scouts to act.
The vote removes "the restriction denying membership to youth on the basis of sexual orientation alone," the Boy Scouts of America said in a statement.
"Today's vote ending discrimination of gay Scouts is truly a historic moment and demonstrates the Boy Scouts of America's commitment to creating a more inclusive organization," said Zach Wahls, 21, an Iowa Eagle Scout raised by lesbian mothers who founded Scouts for Equality, which advocates for gays in Scouting. He traveled to Texas for the vote.
Some Scout officials who participated in the vote said they wish the group could have gone further.
"We are disappointed that it doesn't include everybody," said Alan Snyder, chairman of the board of the Western Los Angeles County Council of the Boy Scouts of America, who voted for the proposal. "Inclusive should be all-inclusive."
The new policy goes into effect Jan. 1.
Jay Mechling, author of "On My Honor: Boy Scouts and the Making of American Youth," said the organization knew it would lose members either way but was cognizant of its future.
"They are attuned to the demographics and understand that everything we know about young people is that cohort doesn't care about sexual orientation," he said. "If you want to understand these decisions, you have to understand the Boy Scouts is first and primarily a business. It has been all along."
A February Boy Scout poll showed deep divisions, with a majority of teen Scouts opposing both bans and 61 percent of all members supporting them.
Gay rights groups have poured resources into the measure's passage, which they called "historic" when viewed as an important step toward eventually removing the ban against gay adult leaders. For this reason, many gay proponents said they are willing to overlook temporarily the obvious awkwardness of the arrangement: Youths who are gay can be out, but the day they turn 18 they can no longer serve in an organization in which it's common for people who were Boy Scouts to remain active as adult leaders.
Polls before the vote showed that large swaths of Scouting families, particularly in the South and the Midwest, wanted to keep the total ban. Some religious conservatives said they couldn't reconcile their beliefs with the resolution approved Thursday, which says the Scouts as an organization does not have a position on the subject of sexual orientation.
The largest sponsor of Scout troops is the Mormon Church, with about 430,000 of the 2.6 million youth in Scouting. Church officials in April said they supported the proposal, calling it a "good-faith effort" and noting that it calls all sexual conduct by Scouting-age youth "contrary to the virtues of Scouting."
The second-largest sponsor of troops is the United Methodist Church. The denomination never took an official position and several leaders were quoted on both sides.
The third-largest is the Catholic Church, which this week released a letter saying it was "hopeful" to stay in Scouting if it could choose leaders who "espouse, accept and promote" Catholic teachings.
Other Christian and Jewish groups have long called for a full repeal of the bans. Among them are the Episcopal Church, the United Church of Christ and Reform Judaism.
Some opponents of same-sex relationships said they are hoping to stay in Scouting by keeping the topic of sexuality off-limits. But Mechling said this may be unrealistic.
"This is why 'don't ask, don't tell' didn't work. The fact is, sexuality is a topic in the Scouts, in a passive, taken-for-granted way. No one thinks twice about a father mentioning his wife. This leaves the gay guy just sitting there," he said.
The Associated Press and Los Angeles Times contributed.