Although the results of the final examination in Indonesia were the dominant factor in determining high school graduation, the public still did not know how the examination was administered nor how results were used to determine student graduation. Despite its importance, no comprehensive studies about its implementation have been conducted. The present study investigates the implementation of school-based assessment (SBA) in upper secondary schools focusing on the development and administration of the English writing test. This particular test was not covered in the English national examination. Twenty-one schools were surveyed, selected through stratified random sampling. In-depth case studies were conducted in three selected schools representing fully implementing school (FIS), moderately implementing school (MIS), and partially implementing school (PIS). The majority were categorized as PIS. This study suggests that the way in which examinations were implemented needs serious consideration, especially in light of the new regulation that student graduations are based on the result of the school examinations and no longer on the result of the national examination.