Florida is the only state with an outright ban on gay adoption. Mississippi bans gay couples, but not single gays, from adopting; Utah requires adopting parents to be married.

Some Florida legislators have been working ¡ª unsuccessfully thus far ¡ª to modify the state's ban and allow gay foster parents to adopt children already in their care.

Measures have surfaced in a few other states that gay-rights advocates fear would restrict gay adoption or undermine gay families.

_In Arizona, the Senate is considering a House-passed bill that would give married couples priority over single people in adopting children who are in state custody. Family Pride, a national group representing gay and lesbian families, says the bill is discriminatory because gays cannot legally marry in any state but Massachusetts.

_In Utah, Gov. Jon Huntsman this week vetoed a bill ¡ª vigorously opposed by gay-rights groups ¡ª that would have allowed biological parents to terminate their child's relationship with third parties, such as same-sex partners. The bill stemmed from a custody dispute between two lesbians; the biological mother sought to prohibit her ex-partner from visiting her daughter.

_In Ohio, conservative lawmakers introduced a bill to ban placement of an adoptive child in a household where anyone is gay. House Speaker Jon Husted does not intend to let the bill advance to a vote, spokeswoman Tasha Hamilton said.

The bill's chief sponsor, Rep. Ron Hood, contends that children raised by gay parents face increased risk of physical and emotional problems. His concerns are shared by many conservative groups which argue that same-sex partnerships are less stable than heterosexual marriages.

The Donaldson study, written by Illinois State University adoption expert Jeanne Howard, acknowledges that research on gay parenting remains relatively scant.

"Still, virtually every valid study reaches the same conclusion: The children of gays and lesbians adjust positively and their families function well," the report says.

The report was funded by the Gill Foundation and the Human Rights Campaign, both active in gay-rights causes. The Donaldson Institute's executive director, Adam Pertman, said the financial sponsorship did not influence the report's findings.

It concluded by suggesting that gay parents could play a major role in reducing the backlog of more than 110,000 children in foster care awaiting adoption.