Abstract
This study aimed to investigate Thai high school students' reported use of SRL strategies and their self-efficacy and to explore the effects of two psychological determinants in writing performance. Data were gathered from 768 Thai high school students in six high schools located in Southern Thailand. Convenience sampling was used in this study. The research instruments included self-report surveys to examine their reported use of SRL strategies and perceived self-efficacy and a given-topic essay writing test to evaluate their writing performance. The results revealed that grade level and writing proficiency were important factors influencing students' reported use of SRL strategies. Multiple regression analyses showed that SRL strategies and self-efficacy had a positive effect on students' writing performance.