Assessing theory of mind (ToM) with reliable and valid measures is important, as ToM plays a significant role in children's social and cognitive functioning. With this in mind, a thorough analysis of the Theory of Mind scale and the Faux Pas Recognition Test was conducted. Over 750 school-age (M age = 7.7) children with disabilities (mild intellectual disability, hearing impairment) and without disabilities took part in our study. The psychometric properties of measures in these groups of children were checked, using confirmatory item factor analysis, reliability, and validity analyses. Thanks to groups' invariance it was possible to compare mean results of children in the groups. Both measures showed well-fitted models with acceptable goodness of fit as well as scalar and strict invariance. An IRT analysis showed significant differences in the difficulty of the tasks in all groups, but the same order of passing tasks in comparison to other studies, conducted in Western countries, has been observed. Our results showed that the tasks were the easiest for children without disabilities, and most difficult for children with mild intellectual disability. We obtained significant and positive correlations between ToM and social skills and language abilities. The findings are discussed in relation to results from other studies in the field.