This Practice Note provides a practical guide to the procedure for collective proceedings in the Competition Appeal Tribunal (CAT), as introduced by the Consumer Rights Act 2015. The scope of the regime is explored, including when a collective proceedings order will be granted, whether it is on an ‘opt in’ or ‘opt out’ basis, the rights of class members and the award of damages. Also, details on the process, how to commence claims, the documentation required and who can act as a class representative.