Using ordering theory, a boolean algebraic measurement model in which item response patterns are viewed as atoms in a boolean algebra with as many generators as there are items being considered, a hierarchy-generative procedure is developed. This procedure relates to the determination of prerequisite relationships between pairs of items. An experiment in which seven Piagetian tasks were administered, and the task response patterns were subjected to an ordering-theoretic analysis, is presented. It is concluded that ordering theory should be a useful tool for the educator or social scientist, and for developmental psychology and Piagetian theory and research, ordering theory should be helpful in providing information on hierarchial structures amidst behaviors. (DB)