The aim of this study was to investigate causes of seasonal food insecurity in Wara JarsornDistrict, Oromia Regional state, Ethiopia. The study employed both qualitative and quantitativernapproach. Household surveys, key informant interview, focus group discussion and documentrnreview was used to collect data. Data was analyzed using Descriptive statistics such asrnfrequency, mean and standard deviation. Multiple regression analysis, Independent t- test andrnone way ANOVA was used among econometric analysis. Food security analysis was alsorncomputed using Household Food balance model. The result revealed that causes of seasonalrnfood insecurity are related to land holding size, possession of farm oxen, economic status, savingrnculture of the household and access to credit. There is low productive asset in the study area,rncredit access is poor, there is no access to fertilizer credit, level of economic activities are poorrnand job opportunities are lacking. To this regard the result of analytical tools revealed, Farmersrnwho have large landholding, farm oxen and livestock and high off farm income have morerndietary energy than farmers who do not have these property or have less; similarly farmers whornhave got access to credit, save their grain or cash, apply more fertilizer, access to extensionrnservices have more dietary energy than their counter parts. Any initiatives which supportrnfarmers to have enough productive resources, strengthening institutions, diversifying incomernopportunity, awareness creation on saving and expenditure related to socio cultural practicernmay mitigate seasonal of food insecurity.