Puberty is a defining time of many adolescents' lives. It is a series of events that includes thelarche, pubarche, and menarche. Primary amenorrhea is the absence of menarche. There are numerous etiologies including outflow tract obstructions, gonadal dysgenesis, and anomalies of the hypothalamic axis. This review's aims are to define primary amenorrhea and describe the various causes, their workups, associated comorbidities, and treatment options. At the end, a generalist should be able to perform an assessment of an adolescent who presents with primary amenorrhea and, if warranted, begin initial treatment.