Two approaches to the application of psychological theories to education might be referred to as domain-general and domain-specific. The domain-general approach seeks a general theory of cognitive and other skills that apply across subject-matter areas. The domain-specific approach seeks to apply specific theories within given domains, such as reading or mathematics. The latter approach is more widely used. But it fails to provide a unified model of learning and instruction. One of the greatest challenges facing modern research in learning and instruction is devising and then empirically testing domain-general theories. This article describes efforts to devise and test one such model, the theory of successful intelligence.