This study examined whether language structure or language proficiency might influence students’ use of evaluative language in written reports, and whether instruction might improve students’ use of evaluative language. Reports in Japanese and in English written by second year Japanese university students, who had received instruction in academic discourse pertaining to critical evaluation, were analyzed for use of evaluative statements. This revealed no disadvantage for use of the Japanese language, which is considered as having a more indirect structure that may make critical evaluation more difficult. English proficiency test scores, however, were found to correlate with production of evaluative statements in English, but not in Japanese, suggesting that inadequate second language proficiency could limit critical evaluation use. The second year students’ use of evaluative statements was also found higher than their first year counterparts’ (who had not yet received instruction), suggesting that such instruction is beneficial for skills development in both languages.