<p>Previous research on strategy-based L2 writing instruction has treated learners as uniform and has not considered individual variables that might moderate the effectiveness of such instructional programs. Motivated by this gap, the present study investigated how participants’ subjective task values and perceived cost associated with L2 writing moderate the efficacy of strategy-based writing instruction in promoting learners’ recruitment of L2 writing strategies in post-intervention writing activities/assignments. To this end, 85 learners of L2 English, assigned to four classes, received L2 writing strategy-based instruction. Before the experiment, participants’ subjective task values, perceived cost, and their self-reported strategy recruitment were investigated. They then received strategy-based instruction focused on metacognitive, cognitive, and social-affective strategies. A comparison of the participants’ pre- and post-intervention strategy recruitment pointed to the potential effectiveness of the strategy-based intervention. Subjective task values and perceived cost were found to moderate the effectiveness of the strategy-based intervention across all strategy types. Additionally, analyses of the think-aloud data revealed that participants with higher subjective task values and lower perceived cost (HV/LC) recruited the instructed strategies significantly more frequently compared with participants holding lower subjective task values and higher perceived cost (LV/HC). Furthermore, task values (i.e., interest, utility, attainment) and perceived cost were shown to contribute substantially to strategy recruitment outcomes across all subcategories. Implications are presented for L2 writing pedagogy.</p>