Summary Parental mental state language is related to Theory of Mind (ToM) development in children. As deaf and hard-of-hearing (DHH) children tend to struggle with this aspect of social-emotional development, promoting parental mental state language seems promising as a means to boost young DHH children’s ToM development. An intervention to teach parents how to incorporate more mental state language into daily interactions with their children has been developed and implemented in the Netherlands. Parents with a DHH child between 2.5 and 5 years old who received family-centered early intervention were invited to participate in the intervention and in a scientific study to assess its effect. Additionally, a group of parents of DHH children with similar characteristics who did not participate in the intervention was recruited as a control group. Parental use of mental state language and children’s ToM skills were assessed in both groups during home visits before and after the intervention. In this presentation, baseline outcomes regarding quantity and quality of parental mental state language use will be discussed and related to DHH children’s ToM. Furthermore, the intervention and preliminary results on its effect will be presented.