Despite its relevance with English language studies, not many studies have been carried out on the effect of self-regulation on writing strategies in Indonesia. This research attempted to test the effect of individual differences, particularly gender and academic interest, on writing strategies based on self-regulation while taking into account the academic interest as a mediator. This research was conducted quantitatively using a correlational design. Data were obtained through online questionnaires distributed to 324 high school students who were studying English as a foreign language in Malang, Indonesia, and were processed using descriptive and inferential multivariate statistical analyses. The results showed that students' usage of self-regulation-based writing strategies was classified as good, and gender differences were found in the use of the 'planning' strategy. However, after inputting variables of academic interest as covariates, gender differences were found in several writing strategies, such as self-initiating, planning, revising, textgenerating, and acting on feedback. Theoretically, this research contributes to explaining gender differences in writing strategies in teaching and learning practices. Teachers are advised to consider gender differences when introducing writing strategies, either explicitly or implicitly.