Two influential theories of intellectual development are reviewed and analyzed: the psychometric framework, based on the factorial composition of intelligence, and the Piagetian model, based on assimilation and accomodation through four stages of intellectual development. A third concept is the componential theory of intelligence, based on information processing models, and consisting of two basic units of analysis, the component and the metacomponent. The component is described as an elementary psychological process which operates on internal representations of objects on symbols; these components are encoding, inference, mapping, application, justification, and response. A metacomponent is described as a higher order psychological process which controls processes related to executing components; metacomponents consist of component selection, representation selection, strategy selection or planning, strategy monitoring, speed-accuracy tradeoff decisions, and solution monitoring. Conclusions were made, based on research using parochial school children in grades 2, 4, and 6 and college level adults: (1) that children show increased use of exhaustive information processing as they grow older; (2) older children are generally less willing to surrender accuracy for speed; and (3) older individuals are more consistent in applying a strategy to problem solving, although there is no evidence of a general strategy shift in time for any age group. Bibliographical references are appended. (MH)