This article argues that supported decision making is ideal for people with dynamic cognitive and functional impairments that place them at the margins of autonomy. First, we argue that guardianship and similar surrogate decision-making frameworks may be inappropriate for people with dynamic impairments. Second, we provide a conceptual foundation for supported decision making for individuals with dynamic impairments, which integrates the social model of disability with relational accounts of autonomy. Third, we propose a three-step model that specifies the necessary conditions (...) of supported decision making: identifying domains for support; identifying kinds of supports; and reaching a mutually acceptable and formal agreement. Finally, we identify a series of challenges for supported decision making, provide preliminary responses, and highlight avenues for future bioethics research. (shrink)