Although the nongraded school idea has had widespread publicity, there is little general agreement regarding criteria for identifying a nongraded school. There is also little available evidence regarding the permanence of the nongraded organization among schools that adopted the innovation. The project considered here developed and validated criteria for the nongraded school idea. Nongraded schools in every State were surveyed as to the extent to which the criteria were present in their programs. Data were also collected relating to the organization, implementation, and persistence of the idea. Additionally, perceived reasons for discontinuing a nongraded program were surveyed and analyzed. Outcomes of the study offer clarification of the nongraded concept, the extent to which this form of school organization exists, and reasons for apparent success or discontinuance. (Author)