Abstract Critical comments have shown to figure prominently in determining the fate of manuscripts submitted to reputable journals. While various studies have explored different facets of this evaluative genre, there has been limited examination in the context of second language and disciplinary writing. Using a discourse analytic approach, this study analyzed a corpus of 160 reviewers’ reports on submissions by Iranian nonnative writers in applied linguistics (AL) and engineering. The aim was to compare how reviewers employ different categories of critical comments to prompt writers to revise their submissions. The findings revealed that reviewers, regardless of discipline, more frequently commented on language-use issues than content-related issues. Among language-use comments, issues pertaining to lexical and syntactical usage of English were more prominent than concerns about discourse and rhetoric. The analysis also indicated consistent patterns in the reviewers’ reports regarding discourse organization and the balance between positive and negative feedback. These findings are discussed in terms of their practical implications for novice and nonnative researchers in the examined fields, offering insights into the rhetorical and disciplinary norms governing peer reviews and the linguistic choices made by reviewers to guide authors throughout the review process. Increased awareness of these issues can facilitate more effective responses to reviewers’ feedback.