This book collects essays on linguistics, on anthropology, on philosophy, on developmental, experimental, and social psychology, and on the neurosciences, with the aim of integrating knowledge about the variability of metacognitive skills across cultures, and of identifying the potential factors accounting for such variability—such as childrearing practices, linguistic syntax and semantics, beliefs about the self, and rituals. In this introductory chapter, the main reasons that make this topic scientifically and culturally important are presented.