To meet the needs of their wide-ranging audiences, journals and editors must publish science that reflects the diversity of the communities they serve. And yet we collectively neglect the importance of optimizing the diversity of peer reviewers. This viewpoint explores the vital economy and identity of peer reviewers, and how these can help improve diversity in peer review. Economy, because this form of labour props up a publishing system, doling out the main form of currency within academia, and identity, because what peer reviewers contribute extends beyond their disciplinary expertise to their sense of self and what they represent: the backgrounds, values, and views they bring to the work of reviewing scientific papers.