This research investigated a measurement among the indicators of writing self-efficacy and self-assessment scales. This research aimed to examine the relationship between the variables forming indicators of the self-efficacy scale and self-assessment scales and the pre-test and post-test treatment that influence the language writer's self-efficacy scale and self-assessment. This research involved 135 students of the University of Pahlawan Tuanku Tambusai, Indonesia. Data were analyzed using the correlation test; the ANOVA Repeated Measures test and the paired Z-test. The result shows that the variables comprising the Language Writer Self-Efficacy Scale and Self-Assessment have a significant and strong correlation (>0.50) overall. Moreover, the post-test treatment significantly affects changes in Self-Efficacy and Self-Assessment Scales
