This study aimed to investigate how 33 preschool teachers' and 30 special educational needs teachers in Swedish preschools documented and described children's speech, language and communication development. The views on concepts as 'scientific basis', 'proven experience' and ways to follow language development for children in need of extra-support were examined. A questionnaire, including open and closed questions on teachers' work in the preschool practice, provided quantitative and qualitative data. Thus, a mixed method of triangulation was applied with concurrent data collection and analysis. The following themes emerged through the analysis: 'Reflected', 'Unreflected', 'Trust/rely on employer', 'Uncertain' and 'Conviction'. There were various systematic ways to follow the language development of children in need of extra-support. This indicates challenges for preschool professions, as the understanding of the meaning of important concepts varied which entails difficulties trying to work in the preschool practice based on these concepts.