As increasing numbers of adults with mental retardation survive into adulthood and old age, they may face decisions about their health care and end-of-life treatment. Advance directives may serve as a tool for communicating one's preferences about future medical treatment. Information about the types, extent of use, and ethical context of advanced directives is provided and four critical issues regarding use of advanced directives by adults with mental retardation and their families are examined: assessment of decision-making capacity, standards for surrogate decision-making, family involvement in advanced directives planning, and constraints on the use of advanced directives. Implications for professionals are discussed, including ways to facilitate advance care planning.