Previous research has shown that learners of English might experience considerable difficulty when giving constructive criticism to peers in instructional settings. Unlike native speakers, they tend to soften their criticism far less frequently while aggravating it far more often, and thus require pedagogical help in this area. The present study examines whether meta-pragmatic instruction facilitates the learning of linguistic resources for softening constructive criticism in an instructed language-learning context. Fifty Vietnamese high-intermediate-level students of English as a Foreign Language (EFL) were recruited for the control and treatment conditions. Over a period of 10 weeks, the treatment group received explicit instruction in eight types of criticism modifiers while the control group did not receive any equivalent instruction. For data collection, the two groups participated in discourse completion tasks, role plays, and oral peer feedback tasks before and after the treatment. The treatment group was also engaged in writing reflective journals, which were later collected and analysed for instances of input noticing. A delayed posttest was conducted for the treatment group five weeks after the experiment in order to investigate whether instructional effects (if any) lasted beyond immediate post-experimental observations. Findings show positive instructional effects on learners' pragmatic performance and are discussed with implications for future research. (Contains 15 tables.)