People with mental retardation have limited capability for constructing and acting on their own ends, norms, and standards. Planning and deciding on their behalf characterise the care they receive. In other words, their situation differs markedly from the way people usually are described in ethical theory. This discrepancy motivates an inquiry of three issues: Firstly, how can we explain the basic moral requirement of showing sufficient and equal respect and concern for all human beings, confronted with the variability of the personal characteristics of people with mental retardation? An answer is offered by invoking that we are all centres of experience, sources of pro and con attitudes, and members of moral communities. Secondly, how far should people with mental retardation decide for themselves and live according to their own plans? The answer should depend on what will produce the best outcomes for them – provided that others are not unreasonably harmed. Lastly, when others should decide nevertheless, how may they still show sufficient respect for those they try to help? To promote their good on a subjective notion of it provides the best answer.