This study explored the development of theory of mind (ToM) in 80 Swedish-speaking 3- to 5-year-olds, a previously unstudied language and culture. The ToM scale was translated and tested in a Swedish context. The results show that the ToM abilities improve significantly with age. In addition, a gender difference was observed for the whole sample, girls outperformed boys, but follow-up analyses revealed that the difference only remained significant for the 4-year-olds. No gender differences were observed at 3 and 5 years of age. When conducting a scalability analysis, the overall Wellman and Liu scale showed less than acceptable scalability. However, when removing the last task of the scale (Real-Apparent Emotion), the fit and scalability was good. The reason for this divergent result is discussed in terms of cultural differences, such as parental and pedagogical practices in Sweden, which might especially focus on developing children's socio-emotional understanding.