This paper is aimed at investigating four children's development of Theory of Mind (ToM) in computation with their social-emotional, cognitive and linguistic developments after their year in pre-school education. In this qualitatively designed research, the case study method has been applied. Data collected from the children, their mothers and their teacher, have been analyzed with the descriptive method. At the end of the research, it can be seen that the children's ToM progressed by at least one level, and one child even progressed by three. The social-emotional, cognitive and linguistic sides of the participating children improved after one year of pre-school education. It is assumed that this progress contributed to the development of children's ToM. Furthermore, the success and failure in the ToM tasks are in evidently related to the demographic characteristics of the children.