False belief understanding was investigated in maltreated (N = 203), low socioeconomic status (SES) nonmaltreated (N = 143), and middle SES nonmaltreated (N = 172) 3- to 8-year-old children. Contrasts among the three groups provided an opportunity to examine the impact of family contextual influences on theory of mind development. Specifically, child maltreatment served as an "experiment of nature" in order to elucidate theory of mind abilities. Two false belief tasks and language assessments were administered. Among children with a verbal mental age of 49 months or greater, maltreatment was related to delays in the development of theory of mind, beyond the influence of chronological age and SES. The occurrence of maltreatment during the toddler period, onset during the toddler years, and physical abuse were features of maltreatment associated with delay in the development of theory of mind. Findings are discussed in terms of the influence of harsh caregiving on the development of theory of mind. Implications for the understanding of normal developmental processes are highlighted.