Using a self-reporting measure, the study examined IBA-related beliefs of Czech preschool teachers (n = 1,004). In addition, it explored the beliefs of teachers who strongly agreed (n = 564) and those who strongly disagreed (n = 67) with the implementation of IBA in preschool classes. The findings show that teachers within the full sample, as well as those within the contrasting subsamples, hold considerably strong beliefs about the potential of IBA for children´s cognitive development. At the same time, teachers are aware of the challenges associated with implementing IBA. Teachers who strongly favour IBA have significantly stronger beliefs in the benefits that IBA bring to children and also have stronger beliefs about the knowledge and skills teachers need for IBA planning and implementation than has the group that strongly rejects IBA. In contrast, teachers who strongly reject IBA have stronger beliefs that IBA cause problems in preschool classes. The group of teachers who strongly favour IBA have higher levels of education and fewer years of practice than the contrasting group. They are mostly younger teachers who received a modern professional education and who are more open to newer instructional strategies such as IBA.