Teens sometimes engage in behaviors that increase their risks of illness, injury, and early death. Engaging in sexual risk behaviors—such as having sex at an early age, having more than one sex partner, and not using condoms or other contraceptives—can lead to unintended pregnancy, sexually transmitted diseases, and HIV infection. Teens are influenced by their parents’ values, beliefs, and expectations of appropriate behavior. Research has largely focused on mothers. However, recent findings suggest that fathers may parent in ways that differ from mothers, and therefore represent an additional opportunity to support the health and well-being of their teens—separate from the influence of mothers. This fact sheet provides information and guidance for fathers on how to help their teen avoid sexual risk behaviors.