This Practice Note considers Part 21 of the CPR which sets out the rules relating to proceedings involving children. A child is any person under the age of 18. The rules state that unless a court has made a specific order that a child can act on their own behalf, a child cannot be involved in proceedings without the appointment of a litigation friend. This rule applies whether the child is the claimant or a defendant. The Practice Note also covers the rules relating to service of a certificate of suitability by a person wishing to act as litigation friend and provides an overview of the different types of claims involving children.