This article sketches a subtheory of human intelligence based on the component construct. Components differ in their levels of generality and in their functions. Metacomponents are higher-order control process used for planning how a problem should be solved, for making decisions regarding alternative courses of action during problem solving, and for monitoring solution processes. Performance components are processes used in the execution of a problem-solving strategy. Acquisition components are processes used in learning new information. Retention components are processes used in retrieving previously stored knowledge. Transfer components are used in generalization, that is, in carrying over knowledge from one task or task context to another. A mechanism for the interaction among components of different kinds and multiple components of the same kind can account for certain interesting aspects of laboratory and everyday problem solving. A brief historical overview of alternative basic units for understanding intelligence is followed by a detailed description of one of these units, the component and by a differentiation among various kinds of components. Examples of each kind of component are given, and the use of each of these components in a problem-solving situation is illustrated. Then, a system of interrelations among the various kinds of components is described. Finally, the functions of components in human intelligence are assessed by considering how the proposed subtheory can account for various empirical phenomena in the literature on human intelligence.