This dissertation described sarcopenic obesity in underactive older female cancer survivors treated with chemotherapy. Using different definitions of sarcopenic obesity identified from the literature, the frequency of sarcopenic obesity; demographic, health, and clinical variables significantly associated with sarcopenic obesity; association of sarcopenic obesity with objective measures of physical fitness and function; and comparison of sarcopenic obesity definitions that explain the most variance in objective physical fitness and function were described. Results show that the frequency of sarcopenic obesity ranged from 0 to 33% across definitions; some demographic, health, and clinical variables were significantly associated with sarcopenic obesity but had inconsistent significant associations across definitions; sarcopenic obesity was significantly associated with maximal leg strength but not measures of physical function; and sarcopenic obesity explained 3-12% of variance in maximal leg strength. Depending on the definition used, sarcopenic obesity may be a prevalent condition in older female cancer survivors and is strongly associated with poor strength compared to women without sarcopenic obesity which is a poor outcome needing prevention and intervention. The results of this study may contribute to clinical nursing practice by helping nurses be able to more efficiently and effectively implement early prevention and intervention efforts in education and therapy in cancer survivors at high risk of sarcopenic obesity. These data may also contribute to nursing science by helping guide investigation into sarcopenic obesity definitions most strongly associated with declines in objective measures of physical fitness and prompt research into longitudinal studies that could reveal the development of sarcopenic obesity changes over time through the course of cancer treatment and throughout cancer survivorship.