Preliminary evaluation of the environmental impact of research undertaken by the CGIAR and its partners. The evaluation was conducted by a two member panel consisting of Michael Nelson and Mywish Maredia, and was completed in October 1999. The study was commissioned by the Impact Assessment and Evaluation Group (IAEG) which became TAC's Standing Panel on Impact Assessment (SPIA) before it was published. The document also contains an excerpt from the summary of proceedings of the CGIAR 1999 Mid Term Meeting where the evaluation results were presented, and a foreword by IAEG Chairman Hans Gregersen. This study may be considered the first phase of a longer term effort, and considers unplanned and unaccounted for environmental costs and benefits attributable to past research. It focuses on evaluating changes in the use, management and conservation of land resources, which the panel believed are likely have effects orders of magnitude greater than any other positive impacts of CGIAR research. Given the shortage of reliable data, the method used was analysis of different scenarios, rather than economic models. The authors concluded that a very large amount of land, in excess of that available, would have been required to equal the increased production of seven mandate crops and permanent pasture attributed to CGIAR research. The study concluded by listing issues for further empirical assessment, questions on next steps, and recommendations on further activity. In view of the large costs involved, it suggested that the CGIAR provide guidance on the depth and breadth of evaluation of environmental impact it desired.