Psychosocial adjustment in women with breast cancer. There is a plethora of studies investigating psychosocial adjustment in women with breast cancer, its correlates, clinical course, and prognosis. These studies have been conducted with varying degrees of methodologic rigor. An assessment has been made of the quality of this existing evidence to identify from the best evidence the factors which predict the adjustment status of women with breast cancer. Studies have been reviewed, using methodologic standards for the critical appraisal of studies on prognosis, developed by Sackett and colleagues in the Department of Clinical Epidemiology and Biostatistics at McMaster University (Hamilton, Ontario, Canada). Few of the studies investigating psychosocial adjustment of women with breast cancer meet all of the criteria for reviewing studies of clinical course and prognosis. This review focuses the direction and methodologic rigor required in future investigations. In particular, studies are needed that employ prospective designs and that deliberately measure or control for the extraneous prognostic variables that may affect adjustment. Future investigations need to incorporate adequate precision in measurement so that measures of the psychosocial variables are objective, reliable, and valid. 