In the final analysis, the usefulness of learning research for the explanation of long-term development will be assessed against its success in dealing with the relationship between development and learning histories rather than with short-term learning processes. Short-term learning, by definition, is often of trivial significance to many developmentalists. In this chapter and in Chapter Twenty-Three, however, we recognize the fact that, for many psychologists, learning is the developmental process. To study developmental changes in learning is, therefore, to study psychological development. The research should, of course, be aimed not only at description of developmental changes in learning but also at explanation of these changes and at the optimization of learning processes.