Student teachers' knowledge about children with attention deficit hyperactivity disorder (ADHD) and depression and its relations to reporting experiencing emotions during teaching practice were studied. The participants were 186 teacher education students in Estonia. Student teachers' general knowledge and confidence in knowledge varied a lot. Knowledge about children with ADHD was generally limited. Knowledge and confidence in knowledge were negatively related to reporting negative emotions (anxiety, anger, shame) experienced during teaching practice. Findings are discussed, taking into account recent changes in scientific knowledge about ADHD and depression and democratic changes in schools. As knowledge of special educational needs has become important due to applying inclusive education, the findings also refer to the need for modifications in teacher education curricula.