The major o~iective of the study was to compare the academic achievement of bilingual and monolingual groups. In the study many works have been collected regarding the effects of bilingualism on students ' academic achievement and cognitive development that had been taken place in western immigrant students. This sludy was held in Ethiopia in one ethnic group students of Agaws found in Sekota. Accordingly, samples of 58 bilinguals (41 female and 17 male) and 113 monolinguals (62 female and 51 male) were taken Fom lieutenant General Hailu Kebede junior elementary school that was selected purposejiilly. A screening test was administered for the inclusion of students in the biliilgual and monolingual groups. Altitudes of pupils and teachers were assessed using questionnaires. In addition, the language students ' use with either Fiends or families was assessed. The result obtained in this study is consistent with previous research works and bilinguals were found to be better than their monolingual counter parts afier a t-test comparison was made. The ANOVA result also r'!vealed that a bilingual group with high competency in the two languages scored significantly a higher mean as compared with the rest bilingual groups. J,;loreover, in the sample subjects bilinguals achieve better than monolingual groups on the dependent variable academic achievement. The allitude of students was found to be positive but teachers had a negative attitude towards Himlagna language used as medium of instruction. Depending on the result, responsible bodies should encourage Himtagna mother tongue children to follow education in their first language. In addition, attaining a second language without any cost ofthejirst language has higher significance for the students' cognitive and academic growth