If a peer reviewer’s comments or recommendations result in major modifications to a Cochrane Review and they have the relevant expertise, the Cochrane Review author team may invite them to become a co-author. The invitation must be made after the peer-review process is completed and with the agreement of the existing author team, and they must contribute sufficiently to the Cochrane Review to fulfil Cochrane authorship criteria; otherwise they may be recognised in the Acknowledgements section of the Cochrane Review. Peer reviewers are under no obligation to accept the invitation to become authors.