The timing of natural menopause is a clinically important indicator of longevity and risk of morbidity and mortality. Demographic, menstrual, reproductive, familial, genetic, and lifestyle factors seem to be important in this timing. Smoking, lower parity and poor socioeconomic status are associated with earlier menopause. However, a number of relationships have been inconsistent; others remain largely unexplored. Much remains to be learned about factors that affect follicular atresia and the onset and duration of perimenopause and the timing of the natural menopause. Knowledge about these relationships offers women and their health care providers enhanced understanding and choices to deal with menopause.