There is widespread agreement that our ability to deliver sustainable food security for all will be challenged in three dimensions—population growth, constrained natural resources, and climate change. Investments in agricultural productivity are essential to dealing with these challenges. This suggests that cooperation across these two sets of institutions (FAO and the CGIAR) to take advantage of their expertise could result in better understanding for all. At the same time, neither of these institutions has some of the expertise badly needed to assess the coming food security challenges, so cooperation should extend to a range of research organizations. The paper highlights three types of joint activities—cooperative quantitative modeling, cooperative use of institutional and outside substantive expertise, and sustained cooperation with model intercomparison efforts.