Respect for autonomy is a central moral principle in bioethics. The concept of autonomy can be construed in various ways. Under the non-ideal conceptualization proposed by Beauchamp and Childress, everyday choices of generally competent persons are autonomous to the extent that they are intentional and are made with understanding and without controlling influences. It is sometimes suggested that authenticity is important to personal autonomy, so that inauthenticity prevents otherwise autonomous persons from making autonomous decisions. Building from Beauchamp and Childress’s theory, (...) this article develops a non-ideal authenticity-based conceptualization of personal autonomy. Factors that indicate inauthentic decision-making are explicated, and the full concept is defended from three expected objections. The theory is then tested on a paradigm case which has concerned theorists and practitioners for some time, namely the possible inauthenticity of anorexia nervosa patients’ decision-making. It is concluded that the theory seems to be fruitful in analyses of the degree of autonomy of patients’ decision-making, and that it succeeds in providing reliable action-guidance in practical contexts. (shrink)