With prom and graduation season nearing, Mothers Against Drunk Driving (MADD), in conjunction with other groups, is proclaiming April 21 “PowerTalk21 Day” to encourage parents and teens to talk about alcohol.

Laura Dean-Mooney, national president of MADD, tells USA Today that parents are the number one influence on teens’ drinking behavior. The paper points to a University of Michigan study showing that about 70 percent of teens drink during high school years, and 23 percent of seniors admitted to binge drinking in 2010. Alcohol is a major danger to teens who drink and drive or get into cars with drunken drivers, the article notes. MADD’s Dean-Mooney urges parents not to serve alcohol to their children or host parties where teens can drink.

The PowerTalk21 Day is based largely on research by Robert Turrisi, a professor of biobehavioral health at Pennsylvania State University. He says parents should be clear in telling teens that underage drinking is dangerous and against the family rules.

His research has found that parents who talked with their teens about the dangers of binge drinking just before they left for college, did much less drinking in their freshman year compared with students who didn’t have that one conversation with their parents. But, he says, parents and teens should be talking about alcohol many times, and earlier than senior year. He advises parents to resist the urge to lecture, and instead to get their teens to talk about what is going on in their lives.