For teenagers, it appears that sex and drugs do go together, though the annual survey of U.S. teens didn't ask about rock 'n' roll.

Teens who say at least half their friends are having sex are more likely to report having tried marijuana, alcohol and cigarettes, according to a survey released Thursday by the National Center on Addiction and Substance Abuse (search) at Columbia University.

The survey asked teens between 12 and 17 about their use of illegal substances. Researchers then looked at other teen activities to see if those who used drugs had anything else in common.

"This year's survey reveals a tight connection between teen sexual behavior and substance abuse," said Joseph A. Califano Jr., president of the Columbia center.

"Parents who become aware of certain dating and sexual behavior by their children should be alert to the increased likelihood of substance abuse," he said.

In a separate effort to discourage underage drinking, the children's cable TV channel Nickelodeon and an advocacy group, The Century Council (search), announced an initiative Thursday to reach out to kids and parents. "Ask, Listen and Learn" aims to educate kids about the issue and to help parents talk with their kids about underage drinking. It is to include booklets, Web sites and TV public service ads aimed at both groups.

Unlike other surveys, the one by the Columbia center did not ask teens about their own sexual activity, but asked them to estimate how many of their friends were sexually active. It was conducted this way because the ethical review board that oversees the center would not approve of a direct question, said Lauren Duran, a spokeswoman for the center.

Researchers compared teens who reported that at least half their friends are sexually active with those who said that none of their friends are. About one in four teens reported at least half their friends are sexually active; about four in ten said none are.

The study found that the first group is:

—More likely to have tried alcohol, 66 percent vs. 10 percent of those whose friends don't have sex.

—More likely to have gotten drunk at least once in the past month, 31 percent vs. 1 percent.

—More likely to have tried marijuana, 45 percent vs. 2 percent.

—More likely to have tried cigarettes, 45 percent vs. 8 percent.

The survey also found that the more time teens spend with their boyfriends or girlfriends, the more likely they are to smoke, drink and use drugs.

No matter what their behavior, teens said that smoking, using illegal drugs and getting drunk are not cool. More than 80 percent said each of these activities make a teenager "seem like a loser." About 10 percent said the activities make him or her "seem cool."

The telephone survey of 1,000 teenagers was conducted between April 16 and May 16, 2004. The margin of error is plus or minus three percentage points for the entire group, larger for subgroups.