Has Piaget's Construct of Formal Operational Thinking Any Utility?

S ummary . The relation between Piaget's logical theory of formal operational thinking and his account of cognitive development is discussed. The consistency of the latter is tested by a factor‐analytical study of the performance of 481 14‐year‐olds on five formal tasks. The content and concurrent validity of the group tests developed is reported, together with test‐retest and internal consistency reliabilities. Formal operational thinking was found to be a unitary construct, and both heterogeneity of performance and décalage were found to be smaller than a recent review had suggested. Yet it was concluded that a theory possessing predictive power is still elusive.