Manuscript revisions typically occur at two points: Some journals ask authors to make revisions as a condition of having the manuscript reconsidered or accepted, and some journals require changes as part of final editing before the manuscript is published (and some require both). Some journals have policies—or the resources—to help authors make the revisions, but many do not. And a few do substantive editing, while others do only the most basic copyediting. These processes are, in part, the link between peer reviewers' comments and editors' decisions and also, in part, the journal's contribution to improving good manuscripts. In deciding whether to publish a manuscript, editors may accept manuscripts as submitted, reject them, or, most often, offer authors the option of revising their manuscripts before a decision is made. Editors have a range of reasons for offering that last option and for choosing which revisions to request or require. In making these decisions, editors must maintain a balance between the appropriate use of the reviewers as advisers, the rights and responsibilities of authors, and the rights and responsibilities of editors. Editors' concerns include factors intrinsic to the study described in the manuscript (methodologic standards, for example) and others that are outside the authors' sphere, such as the focus of the journal, the nature of its readership, articles recently published in the editor's and other journals, and the special interests that the editor or journal is emphasizing at a particular time. Reviewers play a role in manuscript revision because they have often provided comments about revisions that are necessary before a manuscript can be accepted for publication. Because it is in everyone's best interest to publish the best possible manuscripts, reviewers are expected to provide constructive comments to authors about improving the manuscript and clear guidelines to the editor about the general nature of revisions that would improve the manuscript.1 The editor uses part or all of these comments in giving instructions about revisions. Editors have the responsibility to be clear and forthright about the revision decision and their instructions. Once the decision is made to offer an author the option to revise a manuscript, the editor should send a first letter that spells out the editor's offer and expectations. The letter should lay out explicitly the nature of the offer being made. For example, is the manuscript being rejected in its present form but with the offer of reconsideration if certain revisions are made? Or, in contrast, is the manuscript accepted for publication contingent upon certain revisions' being made? Also in the letter, the editor should give unambiguous instructions about the revisions, including which are required, which are encouraged but not required, and which are optional. Further, the editor should resolve any conflict between different reviewers' comments, so that the author will know which comments are to be followed in making particular revisions. The letter also should outline clearly what will happen after the revised manuscript is received. For instance, will it go out for further review, or will the next decision be made by the editor alone? Finally, the letter should set out a time line or a deadline for the author's reply. After a manuscript is accepted, final editing is required before publication.1 The depth and extent of this editing vary widely from journal to journal. The editing may be simple copyediting (correcting punctuation and spelling, for example) or may be moderate editing for clarity, or for accuracy in the parts where inaccuracies tend to be found (such as abstracts,2 quotations and references,3,4 and the use of statistics5). Sometimes the editing is deep substantive editing (such as reorganizing structure for internal consistency, for instance). The difference is due mostly to the journal's financial resources but also to its traditions. In some cases, especially in small journals where the editor has no editorial staff, any editing is done by the editor, with the authors sometimes having much and sometimes little input, while the publishing house provides typesetting services only. At many journals, the only editing is done by the publishing house, which provides standardized technical editing to ensure that a manuscript is put into correct grammar, consistent spelling and punctuation, and the journal's format; in this case, the author usually has no input. At a few journals, an editorial staff provides substantive editing. The onus for the revising done during the final editing often falls on the author, because most journals do not have staff editors. Authors should be prepared to seek outside editing help from editorial staff at their universities or from private editors (“author's editors”).