The question of developmental synchrony within the concrete operations period described in Piagetian literature was investigated. The idea of synchrony has been challenged by Brainerd's initial groupement research, which indicated a two-dimensional structure, corresponding to class operations and relational operations. A review of the literature indicated conflicting views concerning the nature of synchrony and how it may best be investigated. The secondary issue of distinguishing which groupements were operationalized by several traditional Piagetian tasks was explored. Indications from this study were (1) that the class-relational distinction was not a clear-cut one; (2) considering absolute difficulty level, groupements I, II, and III were more difficult than the other five groupement tasks; however, groupement IV, also a "class" task, indicated an intermediate difficulty level in the older grades; (3) traditional Piagetian performance does not appear to be completely subsumed by the groupement tasks; and (4) nonmetric scaling and clustering techniques aid in the analysis of dichotomous, developmental data. (Author/BJG)