Human development is embedded in various social contexts, such as family, peers, and cultures. Since Bronfenbrenner's theoretical work, many developmental psychologists have investigated environmental influences on human development. In this article, we review the research investigating how social environments interactively affect the development of theory of mind (i.e., the ability to attribute mental states to oneself and to others). We first introduce Bronfennbrenner's ecological systems theory of human development. Based on his socio-ecological perspective, we review previous research discussing the relationships between proximal (i.e., parents and siblings) and distal environments (i.e., socio-economic status, culture, and educational system), and the mental state understanding of children. Finally, we discuss future directions of developmental research in this area and potential applications in education.

Key words: theory of mind, ecological systems theory, young children