This study focuses on parent–child book reading and its connection to the development of a theory of mind. First, parents were asked to report about frequency of parent–child storybook reading at home. Second, mothers were asked to read four picture-books to thirty-four children between 4;0 and 5;0. Both frequency of parent–child storybook reading at home, and mother's use of mental state terms in picture-books reading tasks were significantly associated with success on false belief tasks, after partialling out a number of potential mediators such as age of children, verbal IQ, paternal education, and words used by mothers in joint picture-book reading. Among the different mental state references (cognitive terms, desires, emotions and perceptions), it was found that the frequency and variety of cognitive terms, but also the frequency of emotional terms correlated positively with children's false belief performance. Relationships between mental state language and theory of mind are discussed.