Agricultural investments made bydeveloping countries and multilateral development banks(MDBs) have declined in recent decades. This decline isassociated with a slowdown in the growth of agricultureproductivity. Most development institutions have recognizedthe damage caused by this past neglect, in part evident inrising food prices, and renewed attention to agriculture andagribusiness is emerging. But this renewed interest willneed to deliver results, especially in Sub-Saharan Africa,where the MDBs have had the least success but where theneeds and opportunities are enormous. This paper synthesizesrecent work by the independent evaluation agency members ofthe Evaluation Cooperation Group (ECG) and incorporateslessons from related research by MDBs and from the academicliterature on agriculture and agribusiness. The objectivesof the paper, in addition to distilling evaluative lessonsfor agriculture and agribusiness, are to examine the keyconstraints on the sector and to provide evaluators,operational staff, and policy makers with an evaluativeperspective on interventions in countries at differentstages of development.