This chapter presents evidence that mechanisms relating to the cognitive unconscious: mental structures, processes, and states that can influence experience, thought, and actions outside phenomenal awareness and voluntary control make an important contribution to intelligent behavior. There have been some recent studies that look at individual differences in the cognitive unconscious. The chapter focuses on individual differences and reviews recent empirical work on relations among the cognitive processes underlying psychometric intelligence and the cognitive processes underlying the cognitive unconscious, attempting to bridge two major research programs that, until recently, have traveled on separate but parallel paths. The dual-process theory of human intelligence aims to integrate modern dual-process theories of cognition with research on intelligence. By fostering collaborations across the various areas of psychology and related disciplines, and incorporating dual-process theory into thinking, one should be able to come to a fuller, more complete understanding of human intelligence.