Background: A subset of children with Developmental Language Delay (DLD) encountered difficulties with the regulation of spoken discourse. In the conversations of caretakers with DLD children, several studies report difficulties with turn-taking, a proneness to use the non-verbal register, child and caretaker problems with topic management. Longitudinal research has yet to be conducted on the conversational behaviour of young DLD children and their caretakers. Aims: The study investigates the development of style and structure of conversations between preschool-aged DLD children and their caretakers. Method & Procedures: In a longitudinal design, language samples from twelve DLD children and six Normal Language-Acquiring (NLA) children and their caretakers were recorded in semi-structured play situations at two-month intervals across a period of 18 months. The children were between 2 and 3 years of age at the start of the study. Outcomes & Results: The data show that the DLD children predominantly use restricted linguistic forms, non-verbal register and experience difficulties with turn-taking, topic initiation and topic maintenance. The conversational style of the caretakers in dialogue with their DLD children consistently showed more attention-gathering turns, formulaic corrections, self-repetitions and re-introductions of topics when compared with the conversational style of caretakers in dialogue with their NLA children across the 18 months. Conclusions & Implications: Caretakers in DLD dyads appear to develop a less facilitative conversational style and a decrease of contingencies in initiations and responses over time. The result is little opportunity for the conversational and linguistic skills of the DLD children to develop. Parental guidance in the form of conversational training, child-adjusted register, contingent response behaviour and the provision of language materials which can help the child discover his or her role as a conversational partner and recognize the different perspectives of conversational partners is emphasized. (Contains 8 figures and 9 tables.)