 This Entry will proceed as follows. Part 1 will discuss disability and well-being. It will begin by reviewing debates on the application of three standard accounts of well-being to disability. It will note the divergence between first- and third-person assessments of the impact of disability on well-being under all these accounts and suggest some reasons for this divergence. We will then examine what we regard as the most difficult challenge to the claim that many or most disabilities do not necessarily reduce well-being: the widely-held view that it is desirable to prevent, correct, or mitigate disabilities, and generally undesirable to acquire one. The concluding section of Part 1 will examine how assumptions about disability and well-being inform a number of contemporary debates in medicine and health care.