Record numbers of Americans in a new ABC News/Washington Post poll support gay marriage, say adoption by gay couples should be legal and see gays and lesbians as good parents. Most oppose a right to refuse service to gays, including on religious grounds. And, by a closer margin, more also accept than reject gay marriage as a constitutional right.

The results continue a dramatic transformation of public attitudes on the issue, led by political, legislative and court-ordered developments alike. Seventeen states now allow gay marriage, and federal courts in four others - most recently Texas and Virginia - have rejected laws banning it.

See PDF with full results and charts here.

Support for gay marriage has advanced from 32 percent in 2004 to a majority for the first time three years ago and on to 59 percent in this survey, a new high. Opposition, at 34 percent, is down by 6 percentage points since last summer and 13 points in less than a year and a half.

"Strong" support for allowing gays and lesbians to marry legally, moreover, now exceeds strong opposition by 15 points, a record positive gap in intensity of sentiment. By contrast, strong opposition held sway by a vast 34 points in a similar question nearly 10 years ago.

Other changes in this survey, produced for ABC by Langer Research Associates, are equally profound:

• In a Time/CNN poll in 1992, just 29 percent of Americans supported allowing gay couples to adopt children. That advanced to 49 percent in an ABC/Post poll in 2006 - and to 61 percent now, a sizable majority.

• In a question posed by a Newsweek poll in 1996, 57 percent said gays "can be as good parents as straight people." Today, 78 percent say so, a 21-point jump.

• Sixty-five percent, another high, say being homosexual is just the way people are, rather than the way they choose to be - similar to a year ago (62 percent) but up from 49 percent when first asked by ABC/Post polls in 1994. The number who see being gay as a choice has ebbed from 40 percent two decades ago to 25 percent now.

Further, with the subject clearly headed back to the Supreme Court, a new question in this survey asks whether - regardless of their own preference on the issue - Americans think the equal protection clause of the U.S. Constitution gives gays the legal right to marry. In a closer but still significant division, 50 percent say it does, while 41 percent say not, with the rest undecided.

In another question, 81 percent say businesses should not be allowed to refuse service to gays and lesbians; 65 percent say so even if the business says homosexuality violates its owners' religious beliefs. That refers to controversial legislation approved by the Arizona legislature but vetoed by its governor last week.

The questions on adoption and parenting, for their part, test attitudes on suggestions by opponents of gay marriage that children of homosexuals fare less well than those raised by heterosexuals - an argument currently before a federal court in Detroit.

GROUPS - Some longstanding differences among groups remain, with gay marriage continuing to divide the nation sharply by ideology, partisanship, age, education and religious belief.

Among the largest divisions, support for gay marriage ranges from 82 percent of liberals to just 27 percent of strong conservatives, and from 81 percent of the non-religious to 33 percent of evangelical Protestants.

Seventy-five percent of young adults (under age 30) support gay marriage, compared with 47 percent of seniors; so do 70 percent of Democrats compared with 40 percent of Republicans, and 71 percent of adults with a postgraduate education vs. 52 percent of those who haven't gone beyond high school. There's also a narrower division between the sexes, with women more apt than men to support gay marriage by a 9-point margin, 63 vs. 54 percent.

The partisan and ideological differences play out in other ways. Support for gay marriage ranges from 64 percent in urban areas, which tend to have more Democrats and liberals, to 50 percent in rural areas, with more conservatives. Similarly, 65 percent support gay marriage in the so-called blue states won by Barack Obama in 2012, vs. 48 percent in Mitt Romney's red states.

Divisions on other questions are similar. Viewing gay marriage as a constitutional right peaks, at 67 to 71 percent, among the non-religious, young adults, liberals and postgraduates; it bottoms out at 22 percent of strong conservatives, 29 percent of evangelical Protestants and about four in 10 Republicans, older adults and rural dwellers.

At the same time, there are few groups in which majorities oppose allowing gay or lesbian couples to adopt a child - strong conservatives and evangelical Protestants - and none in which majorities (or even more than a third) say gays can't be as good parents as straight people.

METHODOLOGY - This ABC News/Washington Post poll was conducted by telephone Feb. 27-March 2, 2014, in English and Spanish, among a random national sample of 1,002 adults, including landline and cell-phone-only respondents. Results have a margin of sampling error of 3.5 points, including design effect.

The survey was produced for ABC News by Langer Research Associates of New York, N.Y., with sampling, data collection and tabulation by Abt-SRBI of New York, N.Y.