This paper was prepared to present at the Farmer First Revisited: 20 Years On conference at the Institute of Development Studies, University of Sussex, UK, December, 2007. Its focus is the challenge of strengthening agricultural innovation systems. The paper prefaces this discussion by reflecting on an apparent paradox. While agricultural innovation has never been better studied and understood, many of our ideas about innovation have failed to fundamentally change the institutional and policy setting of public and private investment intended to promote innovation for development.