NEW YORK - First comes love, then comes marriage. Now adoption lawyers and agencies in New York say they're getting ready for a baby boom as same-sex couples emboldened by the state's new gay marriage law take the next step and try to adopt children.

New York will allow same-sex marriages beginning July 24, becoming the most populous state to legalize such weddings. Thousands of couples are expected to tie the knot.

The state already permits unmarried couples, both gay and straight, to adopt children. But a wedding ring is an important milestone in a relationship - and can also bolster a couple's case as they try to impress social workers, adoption agencies and birth mothers during the often competitive adoption process, couples and adoption experts say.

"It's sort of the next natural progression," said Jonathan Truong of Brooklyn, who decided to adopt a boy after marrying his longtime partner, Ed Cowen, in Canada. "You have that feeling of wanting to be in a family."

Experts won't know for sure whether adoptions have increased in the five other states, plus Washington, D.C., that have legalized gay marriage until the results of the 2010 census are released this year, said Gary Gates, a demographer at the Williams Institute, a think tank at the University of California-Los Angeles.

But nationwide, about 19,000 gay couples had adopted children as of 2009, he said. That's up from 10,700 couples in 2000 - the same year Vermont began offering civil unions and four years before Massachusetts became the first state to legalize same-sex marriage.

"I think they will feel more entitled to be a family under the new law," said Susan Watson, director of US adoptions at the Spence-Chapin adoption agency in Manhattan.

The prospect has alarmed conservative religious groups that consider same-sex relationships and parenting immoral.

"Sanctioning such unions as 'marriages' only makes the violation worse; and adding children to the mix, worse still," said Avi Shafran, a spokesman for the Agudath Israel of America, an Orthodox Jewish group.

For lesbian couples, the road to parenthood is relatively easy. All that's needed is a sperm donor or a cooperative male friend who will agree to terminate parental rights when the baby is born. The other partner then adopts her partner's child through a "second-parent" adoption.

The new marriage statute will make the second-parent adoption unnecessary under New York law. But most adoption lawyers are recommending that parents do it anyway to protect themselves if they travel or move to a state that doesn't recognize gay marriage.

"The state where you're vacationing may not see things the same way," said Nina Rumbold, an adoption lawyer.

For men or for women who can't conceive, the process is more complicated.

Cowen and Truong said the urge to start a family began after they got married in Vancouver, British Columbia, in 2005. They looked into hiring a surrogate mother, but that route was expensive and fraught with legal hurdles. New York prohibits surrogacy-for-hire, so they must be done in another state.

Adopting from another country was a difficult option because most countries bar same-sex couples from adopting.

The couple decided to try for an American baby and began the months-long process of applying to be parents. There were forms to fill out documenting both men's background and finances. Then a social worker came to their Brooklyn apartment and did a long interview.

Next came the hunt for a pregnant woman looking to give up her baby. To get around the long waiting lists at many New York adoption agencies, many couples advertise themselves directly to mothers through classified ads and websites.

Cowen and Truong bought newspaper ads and rented a toll-free number. Worried about spooking young mothers, they hired an answering service to explain to callers that they were a gay couple.

They were surprised to find that many didn't care.

"A lot of them were brought up without a father in the home, and so they really miss their father and they think the idea of two fathers is amazing," Cowen said.

Other mothers felt that two working men made the household more financially secure, he said. Truong manages the laboratory at a hospital, and Cowen owns an advertising firm.

Less than a year later after starting the application process, the two men were the proud fathers of Franklin, now a bubbly 2-year-old. Truong is "Daddy" and Cowen is "Dada."

New York's new marriage law comes as several other states are wrestling with the issue of adoptions by gay couples. In April, an Arkansas court struck down a ban on such adoptions. Arizona, meanwhile, passed a law giving heterosexual married couples preference.

In Illinois, a Catholic organization that licenses foster and adoptive parents is suing the state over a law barring discrimination against gay or unmarried couples. Three Catholic dioceses have suspended their adoption placement services, following the lead of Catholic charities in Massachusetts and Washington, DC.

"Children do best when raised by a married mother and father," said Peter Sprigg, a policy adviser for the Washington-based Family Research Council, which has fought gay marriage. "Mothers and fathers contribute to the parenting task in unique ways."

In New York, the new marriage law contains a clause allowing religious groups to deny "accommodations, advantages, facilities or privileges" to same-sex couples. That should allow church-affiliated adoption agencies to deal only with heterosexual couples, avoiding the legal controversies that have flared in other states, Rumbold said.

Same-sex adoptions in New York date to 1995, when a state court decision cleared the way for all unmarried couples to adopt.

A 2009 Census Bureau survey showed no evidence of an increase in the percentage of same-sex couples adopting in Massachusetts after that state legalized gay marriage in 2004. But the sample was so small - only about 100 couples - that estimates are very imprecise, Gates said. Figures from the 2010 Census should offer a more accurate look.

The Massachusetts Adoption Resource Exchange, a group that educates families about adopting foster children, said it has seen a rise in the number of same-sex couples seeking information since 2004. They now account for 381 of the 3,360 couples in the group's database, or about 11 percent.

Vincent Russo, a spokesman for Connecticut's probate court system, said judges in that state have noted an increase in same-sex couples adopting since gay marriage was legalized there in 2008.