Caregiver-child conversation is an important platform for children’s development of language and conversational skills and can form the basis for an approach to intervention for children with pragmatic difficulties. While most intervention studies have focused on reporting overall improvements in children’s language and conversational skills as a result of changes in caregiver behaviour, there is limited fine-grained understanding of children’s ability to achieve conversational topic contingency as a result of specific changes in their caregivers’ use of conversational topic turns and/or the facilitative techniques employed by therapists. The studies described in this thesis aim to address this limitation. The following questions are raised: (i) What is the impact of caregiver training intervention programmes on caregivers’ conversational topic turns and facilitative techniques? (ii) What is the impact of caregiver training intervention programmes on children’s conversational topic turns? and (iii) How do specific facilitative techniques impact children’s conversational skills? The first part of this thesis involves establishing the methodology for data transcription and data coding used in the four studies conducted for this thesis. Conversational recordings were transcribed using the CHAT format and conventions. Then a conversational coding system and a facilitative technique coding system were used to code the communicative acts transcribed. The conversational acts coded were topic change (TC), topic extension (TE), topic maintaining responses (TM), and non-relevant responses (NR). The facilitative techniques coded were imitation, expansion, follow-in questions, and follow-in cloze procedures. Inter-rater reliability levels of the transcription and coding of conversational acts and facilitative techniques were high. Study 1 (presented in Chapter 3) was designed to investigate changes following an ‘It Takes Two to Talk’ Hanen programme in the conversations of four caregiver-child dyads where the children had identified language delay. It employed a single subject design and the outcome measures were analysed in three phases: baseline, intervention and follow-up. The outcome measures were the rates of (i) caregivers’ conversational topic turns (i.e., TC, TE and TM), (ii) caregivers’ facilitative techniques (i.e., imitation, expansion, follow-in questions, and follow-in cloze procedures) and (iii) children’s conversational topic turns (i.e., TC, TE and TM). Results showed that all caregivers produced fewer TCs and higher rates of facilitative techniques, while all children produced significantly more TEs following intervention. Individual caregiver patterns of change appeared to be reflected in their children’s conversational skills. This study supports the effectiveness of caregiver group training programmes in improving the quality of caregiver-child conversations and highlighted the importance of investigating individual variations in intervention. Study 2 (presented in Chapter 4) was designed to investigate the changes in conversational skills of three children with features of autism spectrum disorders (ASD) following the dyads’ participation in caregiver-child individual training as part of a multidisciplinary programme for children with ASD. This study employed a case series design and the outcome measures were analysed in two phases (i.e., intervention and follow-up). Similar to Study 1, the outcome measures were rates of the (i) caregivers’ conversational topic turns (i.e., TC, TE and TM), (ii) caregivers’ facilitative techniques (i.e., imitation, expansion, follow-in questions, and follow-in cloze procedures) and (iii) children’s conversational topic turns (i.e., TC, TE and TM). Results of Study 2 showed that one of the three caregivers decreased the rates of TC, and one of them increased the rates of TM following intervention. The caregivers also increased their rates of facilitative techniques (i.e., imitation, expansion and follow-in questions). Concurrently, the children whose caregivers showed positive changes following intervention increased their rates of TCs and TMs. Consistent with the findings of Study 1, high individual variations were observed in the changes exhibited by the caregivers. Study 2 supports the effectiveness of individual training programmes in improving the quality of caregiver-child conversations and emphasizes the importance of investigating individual variations in intervention. Study 3 (presented in Chapter 5) was designed to investigate the qualitative changes made by a child from each of the first two studies. The two children presented with different language levels and aetiologies but both were receiving individualised programmes designed to enhance their conversational abilities. Taking a functional approach to communication development, Study 3 examined how each child (i) collaborated on an activity; (ii) expanded an activity; and (iii) returned to a previous activity or proposed a new activity, through conversational topic turns. Results suggest that the children learnt to collaborate on and expand activities through their caregivers’ repeated use of contingent topic turns (i.e., TM and TE) and facilitative techniques (i.e., expansion, follow-in questions and follow-in cloze procedures). However, they tended to return to a previous activity or propose a new activity when they did not attend to the preceding act or topic, seemed to not comprehend or were not interested in the preceding act or topic, or when their caregivers failed to attend to their preceding act or topic. These findings highlights that while caregivers’ topic turns that are contingent and facilitative help children to advance their activities, caregivers’ topic turns that are non-contingent have the potential to cause the children to end the preceding activity and switch to another activity. Study 4 was designed to compare the effectiveness of expansion, as a technique for facilitating children’s conversational topic turns, with expansion combined with other techniques when implemented by speech and language therapists (SLTs). Using a repeated measures design, this study aimed to compare the effects of expansion alone (EA); expansion combined with wh-questions (EQ); and expansion followed by a cloze procedure (EC) on the conversational skills of eight preschool children with conversational difficulties in conversation with their regular speech-language therapists (SLTs). Results showed that while there were no significant differences in child verbal topic maintaining responses across all techniques, EA elicited a significantly higher number of TEs, more non-verbal TMs and fewer NRs from the children, than either EQ or EC. The positive effects of each technique on the pragmatic appropriateness in conversations suggest that they could be used strategically in language intervention to enhance therapeutic effect. This thesis suggests that caregiver training programmes that focus on following the child’s lead and support caregivers and therapists to use contingent topic turns and facilitative techniques have positive outcomes for children’s conversational development. It also suggested that caregivers’ and therapists’ facilitative strategies that do not obligate responses from the child (i.e., expansion) have better potentials to help the child to expand the scope of conversations than strategies that obligate a response from the child (i.e., wh-questions and cloze procedures). Finally this thesis suggests that family-focussed intervention that follows the child’s lead appears likely to improve the conversational skills of children with a range of diagnoses by helping to address the common underlying features of conversational difficulties.