The Scientific Goals of Ability Research. Principles and Methods in Investigating General Intelligence. The Nature of Primary Abilities. Principles in Drawing the Map of Abilities. The Discovery of Fluid and Crystallized General Intelligence. Higher Stratum Ability Structure and the ``Investment Theory'' of Intelligence. The Natural History of Ability: Distribution and Relation to Sex and Age. The Physiological and Neurological Bases of Intelligence. Ultra-Human Intelligence: Illumination from Evolution of Animals and Machines. The Debate on Heredity and Environment: Abilities in Relation to Race and Culture. The Triadic Theory of Abilities Developmentally Related to Structural Learning Theory. Personality-Ability Interactions and the Prediction of Achievement. Genius and the Processes of Creative Thought. Intelligence and Society. Glossary. References. Index.