Fatigue is a significant health care problem of interest to professionals in many disciplines. Yet, it is poorly understood. Fatigue, as an indicator of adaptation, is examined in relationship to internal and external environmental demands in women's lives. From a secondary analysis of data collected from a large group of women in a Northwest urban community in the U.S., it was found that internal demands such as depression or anxiety are more significantly related to fatigue and vitality than external demands such as negative life events or employment status.