Teenagers in love may be less likely to get mixed up in crime and substance abuse, according to new UC Davis research. But while romantic love seems to help keep teens law-abiding, casual sex can mean trouble.

UC Davis sociology professor Bill McCarthy and graduate student Teresa Casey found that teenagers in romantic sexual relationships had the same low rates of criminal behavior and substance abuse as celibate teenagers.

But when compared with their celibate peers, teenagers who had sex with nonromantic partners were up to 20 percent more likely to have been involved in criminal behavior -- and as much as 58 percent more likely to have engaged in substance use.

"Romantic love may fill a void that occurs in adolescence between the weakening of parental control and the onset of a marital bond," McCarthy and Casey write. "Romantic love might discourage offending by strengthening adolescents' social bond."

The study used advanced statistical techniques and data drawn from the nationally representative Adolescent Health Survey. It is published in the latest issue of the American Sociological Review.