Attention to pubertal development and menstrual health is an important aspect of primary care for adolescents. Textbooks may not provide sufficient evidence-based guidance to facilitate the early detection of gynecologic disease states and conditions. Conversely, the typical guidelines for pubertal development may lead to over-evaluation of normal girls. Chaotically irregular and unpredictable bleeding is NOT the norm during adolescence. On the contrary, although many early menstrual cycles are anovulatory, most adolescents have menstrual cycles that fall within the parameters of 21-45 days. Adolescents with menstrual bleeding that is less frequent than every 45 days, is prolonged > 7 days, or is excessively heavy should be evaluated in order to detect conditions such as eating disorders, polycystic ovary syndrome, and von Willebrand disease. Clinicians who attend to adolescent menstrual cycles can help set the stage for future health.