The intergroup Hodgkin's Disease in Children Study was designed to determine minimum effective treatment for stage I and II Hodgkin's disease in children up to 18 years of age. Accurate staging of the disease was therefore critical. The number of cases in which the surgeons adhered to the principles and details of the protocol staging laparotomy were less than anticipated during the first 3 years of the study. Improvement in protocol compliance increased as the study progressed. The educational efforts by cooperative groups are credited with initiating this improvement.