When the Mental Capacity Act 2005 was introduced, nearly 20 years ago, it was widely seen as an empowering piece of legislation for those who lacked the mental capacity to make their own decisions. Our toolkit starts by reviewing changes in how the Act is applied over time and then introduces a framework for thinking about rights-based practice. The case studies draw on real cases involving both children and adults, although practitioners will be aware the Act applies to young people over the age of 16 and not to children below that age.