This study investigates the role of the Ethiopian Evangelical Church Mekane Yesus (EECMY) in the development of the Oromo language. The main aim of the study is to provide an account of the contribution of this particular church to the maintenance and development of Oromo, which is spoken by the largest speech community in Ethiopia. The study draws on theoretical and methodological frameworks from the field of language planning and development. The main source of data was interviews and focus group discussions conducted with church leaders at different organisational levels and other members of the church community. In addition, documents found in the church archives were analysed. The findings indicate that a number of church activities have contributed to the maintenance and development of the language. These activities include translation and transliteration work of the Bible and other religious literature, literacy and educational programmes, media work as well as use of Oromo in the liturgy and church services. This study also examined the obstacles that hindered the development of Oromo. The main obstacle was the conflict within the EECMY that arose in 1995 over the use of the language. The study unearths the roots of the controversy through a brief historical examination of the church’s attempts to develop the language, despite opposition from the Ethiopian Orthodox Church and earlier regimes, which proscribed the use of the vernacular languages in Ethiopia. Thereafter it focuses on the internal conflict after the change to a democratic government when the situation in Ethiopia became more favourable towards use of vernacular languages. It identifies the causes of the conflict, the way in which it was resolved and the effects which it had on the development of the language. Recommendations are made for further research and some suggestions are given regarding ways to promote the future development of the Oromo language. / Linguistics and Modern Languages / D. Litt. et Phil. (Linguistics)