Students were classified as formal or concrete-operational using a battery of Piagetian tasks, a biology content examination, and a nonscience content examination. Based on the results it was concluded that Piagetian tasks are relatively content-free and can serve as realistic indicators of concrete and formal thinking abilities. (MLH)

Research is described concerning a factor analytic view of adolescent thought in Piagetian context. Included are a description of Piagetian tasks used for determining stage of mental development, studies concerning Piagetian task factor analysis, and the current factorial structure of adolescent thought. (DS)