This essay is about the subject of language development in preschool, where we have focused on the children’s group composition based on age and how that factor affects the children’s language development. The purpose of the study was to find out what experiences active preschool teachers have regarding this subject, this was done through eight audio recorded qualitative interviews. All of the participating preschool teachers were working in preschool classes at the time of the interviews.Our results show that five out of eight preschool teachers would prefer to split the children up into certain age groups to be able to adjust the activities in a more suitable way to fit their ages. The teachers have also shared many opinions and experiences about how the physical and social environment in the preschool should look to promote and encourage the use of the language.By comparing our results to the literature presented in this essay we have come to the conclusion that there are many pros and cons with having both split and mixed age groups and that there is no clear answer as to which is better. What we can conclude, however, is that most preschools seem to have children’s groups of mixed ages.