The current study provided cross-cultural and cross-disciplinary analyses of the distribution of directives in discussion and conclusion sections of English and Persian research articles (RAs) in disciplines of physics, chemistry, counseling, and sociology, representing hard and soft sciences, respectively. To that aim, 80 RAs from both English and Persian journals between 2000 and 2012 were selected. The RAs were textually analyzed to determine the distribution of directives. Findings revealed a significant difference between Persian hard and soft science RAs in the employment of directives, with soft science writers employing directives more frequently in discussion and conclusion sections in comparison with hard science writers. However, no significant difference was found in the distribution of directives across discussion and conclusion sections of English soft and hard RAs. Moreover, findings did not show a significant difference across Persian and English RAs. Overall, results suggest that Persian and English academic writers tend to follow a similar generic and discursive trend in the employment of directives in their discussion and conclusion sections pointing to the universal nature of directives as persuasive strategies employed by academic writers in canonical branches of science. The findings of the present study might raise learners' awareness of the conventions and lexico-grammatical features of academic writing in Persian and/or English RAs.