This study has explored the working language choice of prospective graduate students in some selected public universities of Ethiopia. In Ethiopia, federal offices and institutions, which are accountable to federal governments and four regions along with two administrative cities, have chosen Amharic as their working language. Currently, however, Amharic is not a language of wider communication in some larger regions of the country. Particularly, claims from students of Oromia region of the country concerning the existing language use policy of the country are becoming serious issues on stage very often. The researcher of this study, therefore, has focused on identifying what choice of language they have and in what linguistic domains they want to use. For this study, the researcher has... employed a quantitative and qualitative data collecting method. The data were collected from prospective graduates of Oromo speaking students in three public universities of the country. The universities were selected purposefully based on what languages are profoundly spoken in communities surrounding the universities. Totally 450 subjects were selected to participate in the study, with 150 from each university. Data were collected in questionnaires. The findings of the study have revealed that prospective graduates of Oromo language speakers are poor in grasping, defining, conceptualizing, stating, organizing and analyzing information in Amharic, especially, in reading and writing skills. Therefore, they would be choosing the Oromo language as their working language in their future career by delimiting their working place to Oromia where the working language is Oromo language. As a researcher, I recommend that the students should extend the scope in which the Oromo language is served as a working language in extra regional and federal government institutions.