[영문]The implementation of the 2005 Mental Capacity Act in England and Wales heralds a new era for social work practitioners and researchers. Protecting and empowering vulnerable adults?an important element of adult-care social work?relies on a legal framework that attempts to balance adults’ rights with the desire to protect them. The new Act is part of that framework, addressing the fundamental issue of when and how decisions can be made on behalf of people who lose decision-making abilities (‘capacity’). The Act encompasses the meaning of incapacity and best interests, advance directives concerning treatment, managing people’s affairs and making decisions for them, overseeing the delegation process, and research. In explaining how the Act addresses some of these challenges, the article alerts practitioners and researchers to the key areas in which the Act will make a major impact.