While osteoporosis is a major public health concern, guidelines for diagnosis and treatment of low bone mass in the premenopausal population is lacking. Dual-energy x-ray absorptometry (DEXA) is a poor diagnostic tool to evaluate bone density in this population and the World Health Organization's definition of osteoporosis based on DEXA is not applicable to women before menopause. Bisphosphonates, while commonly used to treat postmenopausal osteoporosis, are not recommended in most premenopausal patients due to their long half-lives and side-effect profiles, therefore limiting the pharmacological interventions available. Secondary causes of low bone mass in premenopausal women include malnutrition, gastroenterological and hepatic disorders, endocrine disorders, and pharmaceutical use as well lifestyle characteristics. It is important to identify these risk factors in young women in order to encourage a lifestyle and a diet that minimize bone loss and to determine when pharmacologic intervention is necessary. In cases of secondary osteoporosis, treatment of the underlying disease process or cessation of the inciting medication, if possible, often results in normalized bone mass. Newer drugs with more benign side effect profiles and new methods of evaluating bone mass are being investigated and are likely to improve the evaluation and management of premenopausal women with low bone mass.