['We sought to determine whether peer reviewers who attend a formal interactive training session produce better reviews.', "Peer reviewers were invited to attend a formal, 4-hour, highly interactive workshop on peer review. Attendees received a sample manuscript to read and review in writing in advance. The workshop included presentations on analyzing a study and the journal's expectations for a quality review, discussion of the sample manuscript's flaws and how to address them in a review, discussion of the reviews written by the attendees, and discussion of real reviews of other manuscripts illustrating key points. The performance of attendees on the basis of standard editor quality ratings (1 to 5) was assessed for the 2 years after workshop attendance. Control reviewers matched for previous review quality and volume were selected from nonattendees of the workshop. In study 1, all average reviewers received a standard written invitation. In study 2, 75 randomly selected average reviewers were personally and actively recruited with intensive follow-up by means of e-mail and telephone calls in an effort to reduce self-selection bias.", "In study 1, 25 reviewers volunteered for the course, were eligible for study, attended, and were compared with 25 matched control reviewers. Of attendees filling out evaluations, 19% thought it somewhat and 81% thought it very helpful. All thought it would improve their subsequent reviews, and 85% thought it would improve their review ratings. The mean change in rating after the workshop was 0.11 (95% confidence interval [CI] -0.25 to 0.48) for control reviewers and 0.10 (95% CI -0.20 to 0.39) for attendees. In study 2, of 75 reviewers intensively recruited, only 12 (41%) of those who said they would attend did. All of the participants thought the workshop would improve their performance and ratings. Test scores at the end of the workshop improved in 73% of participants compared with scores on pretests. The control reviewers' average rating changed by -0.10 (95% CI -0.49 to 0.29) versus 0.06 (95% CI -0.34 to 0.23) for attendees."] Do effect of structured workshop training on subsequent performance of journal peer reviewers?