My research has had a continuing theme: What in mental activity is carried by consciousness and what is nonconscious? The work has consisted of experimental and theoretical analyses ranging from *subliminal perception* and verbal conditioning to intentional action, concept learning, causal reasoning, and explicit-implicit learning. Much of this work has challenged prevailing views. Out of this has come a more general metatheoretical view on which mental episodes--what occurs between sensory and motor transduction--consist of nonconscious mental operations interrelating conscious states, the sole carriers of symbolic contents. In deliberative episodes, propositional contents are interrelated by operations of inference and decision, and in evocative episodes non-propositional contents are interrelated by associative-activational operations. What are conscious and nonconscious in mental activity are very different but inseparable.