Because adolescence typically is a time of preparation for adult roles, considerable attention hasrnbeen paid to the development and expression of achievement during adolescence. Differentrnresearch out comes indicate that personality types and learning styles play role in determiningrnstudents’ achievement. Therefore, the present study was aimed at the investigation of the effectsrnof some personality types and learning styles on high school and preparatory school students’rnacademic achievement. More specifically the major concern of this study was to examine thernrelationship between personality types and academic success; Learning styles and personalityrntypes and Learning styles and classes. Moreover, it also tries to identify whether there is thernmost preferred learning style at among high school students and whether there is significantrndifference among learning styles on the basis of academic achievement.rnFor the study 330 high school and preparatory school students were randomly selected fromrnWayutuka woreda. Data on personality types and learning styles were obtained from personalityrntypes and learning style questionnaires administered to the participants. Data concerningrnacademic achievement of the students was obtained from the high schools record office. Datarnwere analyzed using statistical tools like Pearson product moment correlation coefficient, onernway ANOVA & percentage. The result of the statistical analysis displayed significantrnrelationship between personality type and achievement, significant relationship betweenrnintrovert personality type and reflective learning preference and significant relationship. Thernresult obtained using percentage to differentiate the most preferable learning style at high schoolrnlevel showed reflective learning style as the most preferred while activist was the least preferred.rnOne way ANOVA was computed to see whether there is significant difference on the students’rnacademic achievement due to learning styles and the result revealed that reflective learning stylernwas the best preferred. It was concluded that personality type and learning style along withrnfactors like intelligence and achievement motivation can determine achievement at high schoolrnlevel. Finally it was suggested that teachers should have an awareness of individual difference inrnlearning and appreciate this diversity and treat students accordingly for instance by encouragingrnintrovert students actively participate in learning activities to make them complete whole person