The study, involving 662 African-American sixth and seventh graders from Philadelphia middle schools, is significant because it provides the first evidence that adolescents who receive a scientifically based abstinence-only sex education program were less likely to have had sexual intercourse after two years than those receiving instruction on condom use that made no mention of abstinence.

The research method that was used in the study—known as a randomized controlled trial—is considered by researchers to be the most scientifically rigorous method for determining whether interventions are effective.

The findings, announced by researcher John B. Jemmott III of the Annenberg Public Policy Center at the University of Pennsylvania, also concluded that the abstinence-only intervention had no adverse effects on future condom use.

Critics of abstinence-only programs have argued that they ultimately discourage the use of condoms, and therefore do nothing to halt the spread of HIV and AIDS. Many of those programs promote abstinence until marriage and also raise concerns about the effectiveness of condoms. The Bush administration strongly backs abstinence-until-marriage programs in this country and abroad.

The abstinence message delivered as part of Jemmott’s "Making a Difference" intervention urged the youngsters to refrain from sex until a time in later life when they could handle a sexual relationship. The instruction made no mention of condoms, either pro or con, but discussed the positive consequences of abstinence and taught skills to practice abstinence. As a result of the "Making a Difference" program, "we changed the intention to have sex," said Jemmott, a social psychologist.

Jemmott told the AIDS gathering that all abstinence messages should not be considered identical and "thrown away" as ineffective. Politics and religion should be set aside in the discussions about the value of abstinence ev