Peer reviewers play a role in ensuring the integrity of the scholarly record. The peer-review process depends to a large extent on the trust and willing participation of the scholarly community and requires that everyone involves and behaves responsibly and ethically. Peer reviewers play a central and critical part in the peer review process but may come to the role without any guidance and be unaware of their ethical obligations. Journals have an obligation to provide transparent policies for peer review, and reviewers have an obligation to conduct reviews in an ethical and accountable manner. Clear communication between the journal and the reviewers is essential to facilitate a consistent, fair, and timely review. Ensure that you declare all potential competing, or conflicting, interests. If you are unsure about a potential competing interest that may prevent you from reviewing, do raise this. Competing interests may be personal, financial, intellectual, professional, political, or religious in nature. If you are currently employed at the same institution as any of the authors or have been recent (e.g., within the past 3 years) mentors, mentees, close collaborators, or joint grant holders, you should not agree to review. In addition, you should not agree to review a manuscript just to gain sight of it with no intention of submitting a review or agree to review a manuscript that is very similar to the one you have in preparation or under consideration at another journal.