Concurr. Comput.: Pract. Exp. Concurr. Comput.: Pract. Exp. 1532-0634 Crunching real data on the Grid Groep D NIKHEF, P.O. Box 41882, 1009 DB Amsterdam, The Netherlands Templon J NIKHEF, P.O. Box 41882, 1009 DB Amsterdam, The Netherlands Loomis C Laboratoire de l'Accélérator Linéaire (LAL), Université Paris-Sud, Bâtiment 200, 91898 Orsay Cedex, France 2006 18 925 940 The D0 experiment has used the European DataGrid (EDG) testbed to reprocess real data obtained from the Tevatron collider at the Fermi National Accelerator Laboratory. Pushing the use of the EDG software beyond feasibility studies has produced a set of recommendations for authors of experiment-level software, for producers of middleware and for designers of Grid systems. This paper describes the D0 experience with the EDG software and the resulting recommendations. research-article