Theory of mind research focuses on children's understanding of other people's minds, their desires, intentions, and beliefs. Currently, there is much debate as to what is the substrate for children's theory of mind development; socio-cognitive skills, linguistic development, a simulation of one's own mental states, and the maturation of innate brain structures have all been proposed as possibilities. Few studies have looked at the influences of language and culture on the development of theory of mind. This study compared the performance of 3- and 4-year-old Mandarin-Chinese speakers to that of 3- and 4-year-old English speakers on four theory of mind-related tasks: (1) appearance-reality; (2) Level 2 perspective-taking; (3) an unexpected contents false belief task; and (4) an unexpected transfer false belief task. No significant differences were found between the performance of the Chinese and American children. (Author/KB)