This paper is not intended to be a deeply meaningful philosophical analysis of theory development nor a detailed historical account of the period involved. It is a personal view as seen by a practitioner and researcher during a period of several decades (1950s-1990). From this perspective, the period divides itself nicely into three distinct stages. Firstly, between the mid 1950s and the early 1970% practitioners were trying to describe Piaget's insights in classroom terms (Collis, 1969,1971; Peel, 1960,1971). This period was followed by attempts to explain the Piagetian stage phenomena most often in terms associated with information processing concepts (Case, 1972; Pascual-Leone, 1970). This latter work continued through the 1970s and in to the 1980s and sparked off a period that saw the efforts of the critical reviewers of Piagetian concepts redoubled. These reviews led to more recent expositions which have Piagetian heritage but subscribe to only a few of the original constructs. As an educational practitioner during the whole of the time under consideration, the writer's observations are biased towards'that context.