Selective mutism is an anxiety disorder characterized by a persistent lack of speech in social situations where a child is expected to speak (e.g. in kindergarten or at school) despite the fact that the child can speak in other situations (e.g. at home). Since children with selective mutism do not speak at school, teachers may create a wrong attitude and opinion about the child with this anxiety disorder. Most teachers often think the child is "just" shy, sensitive, and/or stubborn. Some believe that such children are pretending and avoiding participation in teaching and other school activities. The aim of this graduate thesis is to investigate and present the attitudes and knowledge of teachers on selective mutism. This study was conducted on 168 teachers of first to fourth grades of different elementary schools throughout the Republic of Croatia. The data was collected by a questionnaire that was specifically designed for this purpose. Based on the results obtained we conclude that teachers have more favorable and undetermined attitudes on selective mutism. There were no unfavorable attitudes. In addition, teachers who have had students with selective mutism at school have better knowledge and more favorable attitudes about this disorder. Furthermore, this research has not confirmed that teachers who are generally more sensitive and shy and those who consider themselves introverted have other knowledge than teachers who consider themselves extrovert. Research results also show that teachers do not have much experience in previous work with children with selective mutism and that many are not familiar with the terminology and features of children with this anxiety disorder. Therefore, it is very important to raise the level of awareness and to teach teachers about this disorder and its features because teachers have an essential role in recognizing and treating children with selective mutism. Teachers can help strengthen behavioral techniques that are part of the therapeutic process and can also facilitate and reduce anxiety during a child's school stay.