Don't Ask, Don't Tell - the 1993 law that allowed gays to serve in the military only if they kept their sexual orientation private - is now a part of history.
Repeal of the ban took effect Tuesday at 12:01 a.m. EDT.
Some in Congress still oppose the change, but top Pentagon leaders certified that it will not undermine the military's ability to recruit or to fight wars.
Repealing DADT was one of President Barack Obama's priorities, and unlike so many other things on his agenda, he pulled it off earlier this year.
President Bill Clinton tried to repeal the military's full-scale ban on gays in 1993, but ran into strenuous objections of the Joint Chiefs of Staff.
Don't Ask, Don't Tell was enacted as a compromise. Nearly two decades later, Obama had the Joint Chiefs on his side and the policy is out.
The Army distributed a business-as-usual statement Tuesday, saying simply, "The law is repealed," and reminding soldiers to treat each other fairly.
Defense Secretary Leon Panetta and the chairman of the Joint Chiefs of Staff, Adm. Mike Mullen, scheduled a news conference for later Tuesday.
Meanwhile, a bipartisan group of congressional supporters of allowing openly gay service in the military planned a news conference on Capitol Hill.