Figuring out how to steer teens away from friends who encourage undesirable behavior such as substance abuse is a tricky issue, the Los Angeles Times reports. The article points out that unhealthy behaviors such as drinking, smoking or using drugs can seem almost contagious among teens.

Mitch Prinstein, director of clinical psychology at the University of North Carolina at Chapel Hill and editor of the Journal of Clinical Child and Adolescent Psychology, tells the paper that interfering in a teen’s life too much, especially with friendships, can actually make matters worse because it can fuel rebellion. He recommends that parents help their teen develop a sense of identity and feel secure in it—admittedly not an easy task.

Parents need to give teens some independence but still must impose boundaries, recommends article author Valerie Ulene, a board-certified specialist in preventive medicine.  She recommends against trying to split up a friendship if a teen breaks a rule involving friends. Try grounding the teen, she says, allowing him or her to see friends at home under a parent’s supervision, instead of going out with them.