Serious health problems, risky behavior, and poor health habits persist among adolescents despite access to medical care. Most adolescents do not seek advice about preventing leading causes of morbidity and mortality in their age group, and physicians often do not find ways to provide it. Although helping adolescents prevent unintended pregnancy, sexually transmitted infections, unintentional injuries, depression, suicide, and other problems is a community-wide effort, primary care physicians are well situated to discuss risks and offer interventions. Evidence supports routinely screening for obesity and depression, offering testing for human immunodeficiency virus infection, and screening for other sexually transmitted infections in some adolescents. Evidence validating the effectiveness of physician counseling about unintended pregnancy, gang violence, and substance abuse is scant. However, physicians should use empathic, personal messages to communicate with adolescents about these issues until studies prove the benefits of more specific methods. Effective communication with adolescents requires seeing the patient alone, tailoring the discussion to the individual patient, and understanding the role of the parents and of confidentiality.