It is a right enshrined in the UN Convention on the Rights of the Child that, wherever possible, healthcare decisions should be made in consultation with the children and young people they affect. Unfortunately, a range of barriers can prevent this happening, such as the individual beliefs of healthcare professionals or parents or carers, logistical factors such as time and space, or service-related barriers such as service design or local policies. This guideline aims to put children and young people at the centre of decision-making about their healthcare. While some children and young people may feel they are able to express their views and make decisions, others may feel they do not have the confidence, power or ability to do this and so their voices are not heard. The aim of this review is to identify evidence-based methods to empower children and young people to be effective self-advocates, and make recommendations on how children and young people can be supported to advocate for themselves.