Adam Pertman, executive director of the Evan B. Donaldson Adoption Institute, predicted the holdouts would grow fewer in number as more homosexuals try to become parents.
"It's safe to assume this is a trend that is headed upward in a very consistent way," Pertman told CBS Radio News, adding that more and more adoption agencies feel gays make good parents.
"Their experience is evidently showing that gays and lesbians, as the research indicate, are making good parents, and so they are going back to the parents who are successful for them for children who are waiting for homes," he said.
Debate over parenting by gays has been an important element in the broader dispute over whether to permit same-sex marriage. Opponents of gay adoption say children do best growing up with both a mother and father, and they contend same-sex marriages would make it easier for gays to adopt. Supporters say gays, whether single or as a couple, can provide a loving home for children who otherwise would be in institutions or foster care.
"The child who's older, who's of color, who has special needs, those are the children who are more likely to be adopted by gays and lesbians," said Pertman.
The Donaldson Institute survey did not attempt to estimate the number of children adopted by gays; instead, it surveyed 307 adoption agencies — 277 private and 30 public — regarding their policies.
According to the survey, 60 percent of the agencies accept applications from self-identified gays and lesbians, and 40 percent of the agencies have placed children with such parents.
Attitudes also varied according to the agencies' focus. Pertman said some agencies are more likely to accept adoption applications from gay couples than some others.
"Agencies that deal with children in foster care, that is, public agencies, and agencies that deal with adoptions from abroad, are the most likely, along with Jewish- and Lutheran-affiliated agencies," he said.
Other agencies that were affiliated with religious denominations were less likely to welcome applications from gays, according to the survey.
About half the agencies said they routinely informed birth parents before placing a child with a gay adoptive parent. About one-fourth of the agencies said some birth parents had objected to such a placement or specifically asked that their child not be placed in a gay-led household.
Though a majority of agencies worked with lesbians and gays, only 19 percent made specific efforts to seek them out, the survey found.
Overall, the institute said the findings were good news for gays who want to become parents.
"For homosexuals wishing to become parents, the results paint a more encouraging picture than is often portrayed or perceived," the survey summary said. "Although stereotypes and misconceptions still perpetuate policy and practice... the willingness of adoption agencies to accept gay and lesbian adults as parents means more and more waiting children are moving into permanent, loving families."
Data for the survey was collected in 2001 and 2002, then compiled and assessed for the adoption institute by David Brodzinsky, a psychology professor and adoption expert at Rutgers University.
Florida is the only state that explicitly bans adoption by any gay person; its law is being challenged by gay foster parents backed by the American Civil Liberties Union. Mississippi bans adoption by gay couples, while Utah forbids adoption by any unmarried couple, including gay couples.
In August, the American Bar Association approved a recommendation that all states and courts allow gay partners and unmarried heterosexual couples to adopt children together.
Such adoptions give both parents legal rights and allow children to qualify for inheritance and other benefits from both parents. Currently, many states allow only one unmarried adult to adopt a child, even if the child will live with two adults who act as parents.
The spread of gay adoption had been opposed by many conservative organizations, who say the practice puts gay-rights objectives ahead of children's best interests.
"Unmarried and homosexual partners simply cannot provide the stability that married heterosexual couples can give," says a position paper on the issue by Concerned Women for America.
Officials in Florida have taken a similar stance in defending their ban. Attorney General Casey Walker argued in court that the state has a right to legislate its "moral disapproval of homosexuality" and its belief that children need a married mother and father.