A reliable and valid multidimensional instrument for measuring quality of life in cancer patients has been developed. Furthermore, a model has been offered that describes how quality of life works as an outcome variable. Using this model, predictions were made of how nursing interventions may directly or indirectly impact on quality of life. Initial testing of the model using data from 135 colostomy patients showed how satisfaction with nursing care and personal control act as cognitive mediators of self-worth, which then impacts on dimensions of quality of life.