Tef is a hugely important crop in Ethiopia in terms of both production and consumption. Demandrnforitefihasiriseniandiisiexpecteditoicontinueitoiriseidueitoipopulationigrowth, average incomes,rnandiurbanization. However, the tef production system is at a rudimentary stage and largely reliesrnon traditional methods. As a result, the crop yield has not reached at the desired level to achievernhousehold food security. Therefore, this study investigated the tef technology adoption,rnextension, innovation systems and household food security in Central Ethiopia. Given thernmultidisciplinary existence and various research units ranging from national to the individualrnlevel, different data collection and analysis methods were employed. A pragmatist approach wasrnused that incorporated both quantitative and qualitative methods with multiple techniques forrndata collection and analysis. Additionally, secondary data were carefully reviewed and employedrnto supplement the firsthand data. Descriptive statistics and inferential statistics such as one-wayrnANOVA, t-test, and Chi-square tests were used to analyze quantitative data. Moreover,rneconometric models such as endogenous switching regression model (ESR), multivariate probitrnmodel (MVP), ordered probit model, Tobit model, and binary logistic regression model werernemployed. The Household Food Balance Model (HFBM) and other food security measurementrntechniques such as household dietary energy supply (DES), dietary diversity score (HDDS), andrnfood consumption score (FCS) were used.rnResults revealed that the tef innovation system is not well-developed to support the livelihoods ofrnsmallholders due to systemic constraints in the innovation system. Limited capacity of existingrnactors, weak interactions among actors, weak enforcement of institutions, and inadequaterninfrastructure are the structural elements that have constrained the development of tef innovationrnsystem. The weaknesses in the innovation system have limited the development of innovationrnfunctions such as technology development, technology diffusion, entrepreneurship, marketrnformation, resource mobilization, and legitimacy creation. Results further show that performancernof the extension service delivery was significantly affected by weak enforcement of performancerntargets, limited interactions among actors, lack of rewards and sanctions, weak supervision andrnpolitically biased evaluation, limited involvement of DAs and other key actors in planning,rnevaluation, and decision-making process, weak technical competence and work motivation ofrnDAs, lack of adequate facilities for Farmers Training Centers (FTCs), and lack of motorbikes.rnvirnResults also indicate that improved tef technologies have the greatest impact on household foodrnsecurity when adopted in combinations rather than in isolation. Although combination ofrnimproved tef technologies has the greatest effect on household food security, the adoption raternwas found to be low due to various determinants. The study identified education, household size,rnlivestock holding, cooperative membership, credit, extension contacts, farmersâ€˜ confidence withrnthe skills of DAs, perception on economic return, and perception on participation in thernextension service provision positively and significantly influence the adoption of a combinationrnof improved technologies. While distance to the nearby extension office and distance to thernoutput market has a negative and significant effect on the adoption of a combination ofrntechnologies. The study, furthermore, found that the number of improved technologies adopted isrnpositively associated with education, livestock ownership, farm size, cooperatives membership,rncredit, extension contacts, training, farmersâ€˜ confidence with the skills of DAs, farmersâ€˜rnperception on economic return, farmersâ€˜ perception on participation in the extension servicerndelivery. It is inversely related to distance to nearby extension offices and distance to market.rnIt is concluded that the tef production system was not transformed for developing the tef subsector. Transforming smallholdersâ€˜ production system without addressing the systemic barriersrnof the tef R&D and the factors impeding performance of the extension system inhibitsrninnovation. This situation calls for urgent institutional innovation in research, extension, NGOs,rnand other private actors. Therefore, a combination of technological, institutional, and technicalrnintervention would be paramount to tackle the systemic constraints that impeded therndevelopment of the tef sub-sector. Besides, policymakers should be committed to the activernparticipation of other non-state actors through policy support to make research, extension, andrninnovation processes viable and well-functioning and to have more interaction and work in arncoordinated manner. Moreover, actors should have typically promoted the adoption of arncombination of technologies through designing possible interventions for those factors thatrnimpede the use of a combination of improved technologies.