This article discusses the relationship between disease-advocacy groups and the revision process for the Diagnostic and Statistical Manual of Mental Disorders. We discuss three examples in which patient-advocacy groups engaged with the DSM-5 revision process: Autism Speaks’ worries about the contraction of the autism diagnostic category, the National Alliance on Mental Illness’s support for the inclusion of psychosis risk syndrome, and B4U-ACT’s critique of the expansion of pedophilia. After a descriptive examination of the cases, we address two prescriptive questions. First, what is the ethical basis for patient and advocate influence on DSM diagnoses? Second, how should the American Psychiatric Association proceed when this influence comes into conflict with other goals of the revision process? We argue that the social effects of, and values embedded in, psychiatric classification, combined with patient and advocates’ experiential knowledge about those aspects of diagnosis, ethically justify advocate influence in relation to those particular matters. However, this advocate influence ought to have limits, which we briefly explore. Our discussion has implications for discussions of disease categories as loci for social movements, for analyses of the expanding range of processes and institutions that advocacy groups target, and for broader questions regarding the aims of the DSM revision process.