The question whether talking to yourself is thinking is considered from two viewpoints: radical behaviorism and teleological behaviorism. For radical behaviorism, following Skinner (1945), mental events such as ‘thinking’ may be explained in terms of private behavior occurring within the body, ordinarily unobservable by other people; thus, radical behaviorism may identify talking to yourself with thinking. However, to be consistent with its basic principles, radical behaviorism must hold that private behavior, hence thinking, is identical with covert muscular, speech movements (rather than proprioception of those movements). For teleological behaviorism, following Skinner (1938), all mental terms, including ‘thinking,’ stand for abstract, temporally extended patterns of overt behavior. Thus, for teleological behaviorism, talking to yourself, covert by definition, cannot be thinking.