This paper reviews recent social psychological contributions to the metacognitive movement. It is argued that social psychologists have long contributed to the study of “thinking about thinking”, even though their work has not yet been recognized as metacognitive. The present “expansionist” survey suggests that the domain of social metacognition should include: (1) belifefs about one’s own mental states and processes as well as beliefs about those of other people, (2) momentary sensations as well as enduring folk theories, and (3) descriptive beliefs about how the mnd works and normative beliefs about how it ought to work. The contents and origins of metacognitions are inherently social; at the same time, metacognitions are comprised of cognitive elements an are governed by the principles and laws appicable to human thinking in general. Accordingly, whereas metacognitions about self-knowledge may be derived from different informational sources than metacognitions about other people, the processes whereby different types of metacognitions are formed, activated, and applied are essentially the same. Focusing on the social nature of metacognition an the profound relevance of cultural expectations on cognitive performance makes clear the benefits of systematically exploring the cognitive/social interface in reference to metacognitive phenomena.