The growth in home health care in the US since 1970, and the exponential increase in the provision of Medicare-covered home health services over the past 5 years, underscores the need to assess the effectiveness of home health care in society. Conceptual and applied topics and approaches involved in assessing effectiveness through measuring the outcomes of home health care are presented. Definitions are provided for a number of terms that relate to quality of care, outcome measures, risk adjustment, and quality assurance (QA) in home health care. The goal is to provide an overview of a potential systemwide approach to outcome-based QA that has its basis in a partnership between the home health industry and payers or regulators.