Ethiopian agriculture is characterized by smallholders farming whose access to modern technology and basic education is very limited. Research, extension, education and farmers are the main pillars of agricultural knowledge systems and their effectiveness largely depends on strong linkage among each other. However, the existing research-extension-education linkage has not been effective. This very weak linkage has been a major limiting factor to increased food productivity, agricultural transformation and sustainable development. Thus, the purpose of this review is to point out the major challenges for effective linkage between Research, Extension and Education (REE) and propose some recommendations for better linkages. Much of the problems bounce around limited implementation capacity and lack of commitment. Specific challenges include unnecessary competition and duplication of efforts, lack of decentralized approach, failure to involve poor farmers and inefficient monitoring and evaluation system. Thus, policy framework that synergizes the relevant actors' linkage in a sustainable manner should be in place to bring the intended growth and transformation in agriculture through technology and innovation.