The paper describes approaches and findings of an evaluation of 10 advocacy projects providing services to developmentally disabled and mentally ill persons across the country. The projects included internal rights protection organizations, independent legal advocacy mechanisms, self-advocacy training centers, and legal advocacy providers in conjunction with local government. The evaluation process included four instruments used to collect information: individual client profiles, an aggregate client data instrument, a project overview instrument, and a staff time and budget instrument. Findings are summarized according to the following topics: clients served (age, living arrangement), strategies employed (negotiation vs. litigation), cost findings (demonstrating a large range of costs), and efficacy in bringing about broad-based changes in the service delivery systems. Six implications of the finding are highlighted, including that the relationships between mental health professionals and advocates do not have to be adversarial, that advocacy activities are not characteristically confrontational, and that legitimation of advocacy programs in state statutes and/or regulations may ensure their continued existence. (CL)