This thesis is about the impacts of development intervention on customary institutions ofrnfo rest resource management, among the Borana Oromo of Southern Ethiopia. The study isrninitiated as result of observation of deforestation of the Borana forestlands. There are, ofrncourse, natural factors that contribute to the deforestation, such as climate change. But thernprime factors are the inappropriate development interventions into the customary in stitutionsrnof resource management. This led to overpopulation, shrinking of .the Borana land andrnweakening of customary institutions. The results are pressure on forest, competition overrnforest resources and deforestation.rnThe study planned to assess the general impacts of development interventions on costomaryrninstitutions of forest resource management and socio-cultural aspects of the community. Thernqualitative method based on primary and secondary sources were used in data gathering forrnthe study. The primary data were generated from observation, iu-depth interview, focus grouprndiscussion, case study and informal discussion; whereas, secondary data were collectedrnthrough consultation of related literatures. To analyze those data, the researcher used theoryrnof common-pool resources.rnThe results of the study depict that most of the ceremonial grounds and holy trees of thernBorana are sited inside the forest areas. The mobile ritual villages of the Borana usuallyrnreside inside the forests to perform various cultural practices and thus, the belief systemsrnattached to the forest grounds are the basic means of forest management. Moreover, differentrncustomary institutions at various levels and their members are responsible for forestrnmanagement. However, development interventions such as urbanization, state structure andrnpastoral development programs and policies ignored the customary institutions of resourcernmanagement and used the top-down development approach.rnThe impacts of inappropriate development interventions brought erosion of customaryrninstitutions, change ofrange ecology and shrinkage of the Boranaland that led to competitionrnover forest resource and deforestation. Therefore, the thesis has emphasized the need forrnanother alternative to recognize customary institutions of forest management and in such arnway that the forest resources will be conserved wisely. By doing so, there are points to bernconsidered before hand. The usually opposing structures of the customary systems and thernstate at the local level should integrate in the resource management systems. Or, the one thatrnis presumed better in resource management should be given the independent authority tornmanage resources. After all, participatory development approach should be employed fromrnthe problem identification, planning, implementation, monitoring and evaluation phases.