Preeclampsia, a major cause of morbidity in pregnancy, is still a disease of unknown cause, despite considerable research in recent times. We believe that progress in understanding the disorder would be enhanced if the systematic review methodology, similar to that used to assess data from clinical trials, is applied to studies that investigate the many theories advanced to explain its cause. This article discusses the need for and a frame work of such an endeavor. The systematic review approach helps to determine where research should be focused, to prioritize the use of resources, to understand, and then hopefully to conquer a disease that still kills mothers and infants each year, worldwide.