BACKGROUND: The Kansas City Cardiomyopathy Questionnaire (KCCQ) is a well-established instrument used to evaluate the health status of heart failure (HF) patients. There has been a lack of clarity about the best way to conceptualize the KCCQ. The purpose of this investigation of the KCCQ was to: (1) explore the factor structure with an exploratory factor analyses; (2) perform reliability and validity testing to determine the best factor solution for item groupings; and (3) determine the most meaningful components of health status captured by the KCCQ. METHODS AND RESULTS: A secondary analysis of data from 280 adults with stage-C HF enrolled from three US northeastern sites was conducted to test the KCCQ subscale structure. Criterion-related validity for the Self-efficacy subscale was tested with the Dutch Heart Failure Knowledge Scale and the Self-care of Heart Failure Index Self-care Confidence Scale. Overall, internal consistency reliability (Cronbach's alpha) for the KCCQ and subscales was 0.92, social interference (seven items, 0.90), physical limitation (four items, 0.84), symptoms (eight items, 0.86), independent care (two items, 0.80), and self-efficacy (two items, 0.63). Two items failed to correspond to a previously identified factor so the independent care subscale was added. Items intending to measure quality of life were loaded in the social interference subscale. CONCLUSIONS: We recommend eliminating the quality of life subscale and including those items in the social interference subscale, and eliminating the self-efficacy items and re-evaluating the items related to independent care.