This study was undertaken by David Raitzer, on behalf of the CGIAR Standing Panel on Impact Assessment. The author addresses the question: do the documented benefits from CGIAR research justify the total investment in the CGIAR so far? The basic objective of the study is to derive a set of plausible and highly credible aggregate estimates of the benefits accruing from System innovations, and to set such against the present value of the entire CGIAR expenditure. The study contains several figures and tables. The forward was written by Hans Gregersen, Chair of the Standing Panel on Impact Assessment.