This study was conducted in order to describe school-based factorslrncharacteristics that have the most powerfol effect in the determination of students'rnlearning outcomes Hence the main purpose of this paper was to examine, compare andrnidentify the salient differences and similarities exhibited in the two groups of schools,rnselected as high and low achiever schools in the ' National Assessment Study' testsrnconducted by National Organizations for Examinations (NOE) in 199912000 with regardrnto students ' learning achievements ..rnAccordingly, the general conditions of the directors, teachers, and students of thern6 sample schools and the classroom interactions were used as main data sources for thisrnstudy. In collecting the required data, direct observations and questionnaires werernapplied. In line with this the required information was mainly collected from 6 schoolrndirectors, 140 teachers, 480 students, andfrom 36 classroom observations.rnThe collected data was organized, analyzed and discussed based on the researchrnquestions. The result showed many inconsistent differences on distance of schools fromrnzone towns, supports nade by education officials, students teacher ratio, directors'rninstructional support, teachers' feeling on mastery the profession, absenteeism 5rate,rnstudents attitude towards instruction, teachers and subjects. On other areas similarities,rnwere also observed on problems of facilities, instructional materials, qualification andrnexperiences of teachers, classroom conditions, and the teaching styles.rnAs a whole, by answering the research questions, concluding the findings and byrnconsidering the experiences achieved necessary recommendations were given on twornmajor areas what to be improved for schools and what to be stressed for conductingrnfurther studies. Attention should be given to the schools, in supporting them withrnfacilities, equipments, instructional materials, and qualified manpower, and otherrnmeasures have to be taken in solving their problems. The other suggestions indicate thernneed of emphasis on that school based study that should be, used as bases for all otherrnfurther studies as regards to the improvement and effectiveness of schools in particularrnand to the education system in general and on policy concerned issues too. Thus,rnconducting similar studies require repetition not only in a one shot but also in arnlongitudinal dimension