This paper is about the Plank 4 of the new CGIAR Strategy that calls for the adoption, in collaboration with national and regional partners, of a regional approach to research planning, priority-setting and implementation. Given the poverty and impact focus of international public goods research, both NARS and the CGIAR have advantages in pursuing a regional approach as a component of their respective activities. For the NARS in the region, this means seeking at the regional level advantages that they could not derive from a national-level approach, thus complementing and supplementing the national approach. For the CGIAR, this means seeking complementary gains that it could not achieve through a global or ecoregional approach. These mutual advantages open the door for partnerships in regional research between NARS and their regional organizations, and the CGIAR. This paper highlights the advantages and added value of a regional approach to research as well as risks and limitations. The roles of TAC, GFAR and the CGIAR Centres in the regional planning process are briefly described