Even as a bill to continue funding abstinence-only instruction moves forward in Congress, researcher Douglas Kirby said that only a couple of programs that exclusively focus on abstinence have yielded even "modestly encouraging results."

However, many studies have shown that combining the abstinence message with explicit discussions of birth control "is a realistic, effective approach that does not appear to confuse young people," Dr. Kirby said in a report for a nonpartisan group that tries to reduce teen pregnancies.

In Texas, which leads the nation in teen births, backers of the more comprehensive approach applauded the study, but a social conservative was quick to denounce it as "faulty science."

Kyleen Wright of Mansfield, president of the Irving-based Texans for Life Coalition, said that contraception instruction was tried in the schools in the 1980s and didn't work.

"Now, we see a new spin, all these new attacks on abstinence ... trying to discourage parents from supporting what they feel in their gut is right for their children," she said.

Ms. Wright said the release of the report was timed to sway Congress to end federal funding of abstinence education.

Dr. Kirby denied that.

On Tuesday, the House passed a spending bill that would spend $141 million on community-based abstinence education, the level requested by President Bush. Though the Senate approved a smaller amount, proponents of more comprehensive sex education in the schools and wider availability of birth control for teens are unhappy the Democratic Congress hasn't killed the program.

On Wednesday, Planned Parenthood, the nation's largest network of sex education providers, called on Congress to stop funding programs that focus solely on abstinence. It pointed to the Kirby report as "definitively showing" that the programs don't work.

"As the mother of two teenagers, I want my kids to be taught about abstinence, but I also know that that's not enough," said Cecile Richards, formerly of Austin and the daughter of former Texas Gov. Ann Richards, who is president of the Planned Parenthood Federation of America.

In the report, which was based on a review of 115 studies of teenager sexual behavior, Dr. Kirby said abstinence-alone instruction is largely unproven, though he shied away from a sweeping denunciation.

Dr. Kirby, who for decades has evaluated sex-education programs for the government and other groups, conducted the review for the nonpartisan National Campaign to Prevent Teen and Unplanned Pregnancy.

He said two studies had found "weak but encouraging results" from abstinence programs in Ohio and Arkansas. However, he said more efforts to duplicate and study them are needed.

In April, Mathematica Policy Research released a report that was nine years and $8 million in the making. Scientists followed middle school children enrolled in four separate abstinence programs for about five years, and found no difference in the age of first intercourse between them and their peers.

In his review, Dr. Kirby said, "Two-thirds of the 48 comprehensive programs that supported both abstinence and the use of condoms and contraceptives for sexually active teens had positive behavioral effects," such as delaying the start of sexual activity and increasing use of condoms or other birth control.

He found no evidence that supplying youngsters with a dual message – explaining details about birth control and urging that they wait to have sex – "hastened the initiation of sex or increased the frequency of sex."

Dr. Janet Realini, a San Antonio public health official who supports more comprehensive instruction, hailed the study's other findings, such as that programs in which teens do community service or get one-on-one counseling can reduce teen pregnancy.

"There are some new, promising results on programs for parents," she said.