This study examined the effectiveness of written corrective and the role of individual differences (ID) in the uptake of the feedback. Data was taken from a nine-week, English as a foreign language (EFL) writing course from 101 intermediate (n=101) students at a private university in Kobe, Japan. Using an explanatory sequential mixed methods design, quantitative data was first collected concerning writing errors, followed by qualitative semi-structured interviews. Three classes were placed into either two treatment groups (direct and indirect) or a control group, and completed four writing tasks (pre-test, post-test and two delayed post-tests). The study found the two treatment groups showed significant improvements on local and global errors, whereas the control group did not. Additionally, the qualitative component elicited the influence of affective factors. The study adds to the body of literature addressing the impact of written corrective feedback, specifically on students' self-editing strategies.