This study aims at investigating (1) To what extent performance assessment successfully fosters students' learning ownership and writing achievement and (2) Teachers' readiness related to the implementation of performance assessment in writing courses. This study was conducted using a mixed methods approach. Quantitative analysis of MANOVA was used to know the effect of performance assessment on students' learning ownership and writing achievement; while qualitative analysis was conducted for data of teacher readiness gathered using questionnaires and interviews. The subjects of the study were 32 EFL teachers and 82 students of Junior High Schools in Bali. Results of the analysis show that performance assessment significantly affects students' learning ownerships and writing competency; while teachers' readiness in implementing performance assessment largely depends on the availability of assessment instruments which are different from the traditional multiple choice type test.