This study aimed to determine the psychometric properties of the Theory of Mind assessment scale in children (ToMas-child). Two hundred and fifty-two Spanish children from 3 to 7 years were assessed in school settings. Rasch analysis showed the ToMas-child is a unidimensional scale valid for the assessment of the main components of the ToM in children. Data of hierarchical distribution of six items (seven tasks) are discussed as milestones in the latent construct of ToM development in childhood, and construct validity of the scale is examined. A reliability index of PSI = 0.7 indicated the usefulness of the scale as a screening tool.