This thesis attempts to examine the socio-economic history of Sibu Sire woreda to the end of Derg regime in 1991. The thesis begins its discussion with describing the overall background of the woreda. It explores the historical nomenclature and foundation of the woreda in the third decade of the twentieth century. The thesis also deals with the various ethnic groups and their socio-economic interactions during the period under the study. Owing to its vastness and abundant climate condition the study area was inhabited by different nations and nationalities. During Italian occupation of Wollega several ethnic groups came to Sibu Sire woreda and made socio-economic interaction with each other. Additionally, the thesis examines the economic base of the woreda. Agriculture was the major livelihood for the people of the woreda during the period under study. Regarding infrastructural system Sibu Sire got access to social infrastructures (education, health, road and light) in post liberation period. Like other parts of Ethiopia Sibu Sire woreda encountered different socio-economic problems in the second half of the twentieth century. Furthermore, the research deals with the various customary practices of the people in the study area including belief system, marriage practices, funeral and burial system and blood price payment.Besides,the study attempted to deal with the indigenous knowledge of the people in the study area. This research is conducted using three methods of collecting and analyzing historical sources. Collection of oral tradition and oral interview are the major methods employed to obtain data for this research. Informants who have rich information about a socio-economic history of the woreda were very useful for this study.Archival sources are used in this thesis. I have got only some archival material in national archive and library agency at Addis Ababa. The researcher conducted interview based on age, experience to share knowledge, religious and ethnic background of the informants in order to get available information regarding the concerned issues. Besides, published and unpublished written sources (books, articles journals, thesis and dissertations) have been utilized for conducting the research