This research aims to find out the implementation of self-assessment and ability of selfassessment of student with special educational needs (SEN) at inclusive school. This research applies study-case approach to 10 SEN with mental retardation variation, autism, muscular dystrophy, slow learner, and low vision in semester 2 in 2017/2018 school year in Tumbuh High School (THS). This article defines the implementation and ability of selfassessment of SEN viewed from aspects of attitude, motivation, anxiety, concentration, time-management, self-assessment, and searching of learning source. The research results shows that the ability of self-assessment is quite varied since THS applies the medium self-assessment with project strategy adapted from International Middle Years Curriculum (IMYC).