The current study aimed to explore how students’ L2 writing self-efficacy and interest contribute to strategy use and writing performance. An exploratory factor analysis with 212 Korean college students’ self-reported motivation scores revealed three underlying constructs of self-efficacy, communicative interest, and instrumental interest. Subsequent multiple regression analyses indicated significant positive relations between self-efficacy and the five types of strategy use. Communicative interest appeared to positively contribute to use of planning,monitoring, and compensatory strategies. Instrumental interest was a predictor of retrieval and compensatory strategies. L2 writing strategy use was a statistically significant but minor contributor to L2 writing performance. The current study also suggests that students’ instrumental interest and communicative interest should be balanced. Further research is needed to identify mitigating effects of L2writing strategy use for motivation and performance development.