This paper argues that a major aspect of intelligence is the ability to solve problems and that careful analysis of problem-solving behavior is a means of specifying many of the psychological processes that make up intelligence. The focus is on the mechanisms involved when, in the absence of complete instruction, a person must "invent" a new solution to a problem by assembling previously learned skills. To describe this type of problem-solving behavior the authors set forth an information processing model characterized by three classes of processes: problem detection, feature scanning, and goal analysis. A series of studies on invention, in which children are taught component skills and their behavior is examined in situations where these skills must be combined in a novel fashion, elucidates this model. (Author)