Abstract: This paper explores the ethical and conceptual implications of the findings from an empirical study (reported elsewhere) of decision-making capacity in anorexia nervosa. In the study, ten female patients aged thirteen to twenty-one years with a diagnosis of anorexia nervosa, and eight sets of parents, took part in semistructured interviews. The purpose of the interviews was to identify aspects of thinking that might be relevant to the issue of competence to refuse treatment. All the patient-participants were also tested using the MacArthur Competence Assessment Tool—Treatment test of competence. This is a formalized, structured, interviewer-administered test of competence, which is a widely accepted clinical tool for determining capacity. The young women also completed five brief, self-administered questionnaires to assess their levels of psychopathology. The issues identified from the interviews are described under two headings: difficulties with thought processing and changes in values. The results suggest that competence to refuse treatment may be compromised in people with anorexia nervosa in ways that are not captured by traditional legal approaches.