Operation Group Training at the ESRF L. Hardy. ESRF, BP 220 avenue des Martyrs, 38043 Grenoble Cedex. Abstract The ESRF (European Synchrotron Radiation Facility) is a X- ray source of the third generation. The accelerator complex is composed of a Linear accelerator (e- 200 MeV), a synchrotron (300 meters - 6 GeV) and a Storage Ring (844 metres). Only one full-time operator and one volunteer on shift (engineer or technician) operate these accelerators from the Control Room. Therefore a high level of versatility is required of each operator. To achieve this goal, the Operation group training policy focuses on three methods. The first (and maybe the best) method is day-to-day informal dialogue between the Operators and the Machine experts. The second method is for each Operator to deepen his knowledge of the various pieces of equipment and afterwards transmits his knowledge to his colleagues. Finally, the usual internal/external training is considered. This paper will describe the ESRF Operation Group training policy (frequency, level, budget, etc).