This cross sectional study examined the factors associated with social workers' involvement in end-of-life (EOL) planning using a random sample of NASW members in health and aging. Of the 390 social workers who worked in EOL planning, the majority were involved in health care proxy discussions and counseling with patients. Respondents tended to see barriers to proxy completion as client-related. However, some system barriers were correlated with overall involvement. Factors that predicted social workers' involvement with the health care proxy included age, attitudes, perceptions of barriers, and perceived physician support. Social workers need to attend to the systems in which they operate as well as to client concerns.