Inadequate writing skills prevent learners from improving their writing performance and interfere with their subsequent writing performance in real-life scenarios. This study aimed to analyze the effect of metacognitive regulation on authentic writing performance in a web-based constructivist learning environment. The environment maximized the presentation of authentic writing problems that learners faced in their studies and lives. The study used random cluster sampling to draw samples for a single-group pre-test and post-test experiment with 45 students. After that 45 students experimented around two authentic writing topics. The researchers used repeated measures ANOVA to assess the results of the learning achievement data, showing that there was no significant difference between pretest 1 and pretest 2. Posttest 1 and posttest 2 were significantly higher than pretest 1 and pretest 2. In addition to this, the researchers measured the use of metacognitive regulation to intervene in authentic writing learning through metacognitive interviews (process evaluation). The researchers collected and analyzed interview data from the 45 participants mentioned above. The results of the analysis of the metacognitive regulation interview data were consistent with the participants’ learning performance. From the interview transcripts, it was clear that participants perceived metacognitive regulation significantly contributed to authentic writing learning performance. A limitation of the study is that the group of participants in the experiment were all grade 10 students, and the experiment was not conducted among learners of different ages and experiential backgrounds.
