Theory of mind is a social cognitive domain, reflecting the understanding that internal mental states motivate outward behavior, that develops rapidly over the preschool time period. While critical for healthy social development, less is known about the how aspects of the family environment interact to influence this development or the neural mechanisms that support it. Several decades of research have demonstrated behaviorally that aspects of parent behavior and language are associated with theory of mind skill use in early childhood. Many of the earliest social interactions occur with parents within the family context and little research to date has examined how household environmental factors may moderate the associations between parent behavior and language and child theory of mind development. Aspects of household functioning, such as household chaos, may serve to disrupt the positive interactions between parents and children that benefit early social cognitive development. Further, very little is known about the neural mechanisms that support early theory of mind development and how structural differences in the brain may be associated with parent language use. My dissertation investigates the interactions between aspects of the family and home environment on the behavioral development of theory of mind and the neural structures that support this skill in early childhood.