Hospice has become a major component of end-of-life care, but little scientific information is available to guide clinicians in knowing when the use of hospice is appropriate, in knowing how to measure the impact of its care, and in knowing which hospice interventions lead to the best outcomes. The National Hospice Outcomes Project (NHOP) arose from the need to identify patient factors and hospice interventions that are associated with better end-of-life outcomes. Clinical Practice Improvement (CPI) methodology allowed us to generate a large comprehensive database that could identify scientifically hospice interventions associated with better outcomes for specific patient populations. The complex interplay of patients, medical and complementary treatments, and families can be evaluated. This paper describes an overview of the research methods used for the NHOP, describes the project's 13 clinical sites and study population of 1,306 patients, and presents some basic findings from the study.