Family-centred care (FCC) has long been acknowledged as best practice for meeting the needs of families of children with hearing loss (HL) and improving early intervention (EI) outcomes. Although the literature has reported some gaps in service provision to families of children with HL, and the period from the time of diagnosis to enrolment in EI has been identified as a significant decision-making period, there is a lack of in-depth knowledge regarding families' needs during this period. In addition, no study has addressed the current gaps in FCC for children with HL with or without additional disabilities transitioning to EI. Therefore, the overarching aim of this thesis was to develop a family-centred intervention to support families of children with HL transitioning to EI, using an implementation science approach. The specific aims of this thesis were: (1) to explore families' needs in the transition to EI after diagnosis of HL from both families' and professionals' perspectives; (2) to investigate families' and professionals' perspectives on the provision of FCC in the transition to EI; and (3) to develop a family-centred intervention for children with HL-with or without additional disabilities-transitioning to EI. Chapter 2 describes the overarching framework applied throughout this thesis, the Behaviour Change Wheel (BCW). The BCW is a step-by-step guide for planning interventions that involves three tasks, including (a) understanding the behaviour that needs to be changed (Chapters 3 and 4), (b) identifying intervention options (Chapter 5), and (c) identifying implementation options and content of the intervention (Chapter 6). Chapter 3 explored families' needs in the transition to EI using a qualitative approach incorporating semi-structured interviews with families and professionals. Four major themes were identified from the interviews: (1) families require information that meet their specific xi Financial support This research was supported by an Australian Government Research Training Program Scholarship. The authors acknowledge the financial support of the HEARing CRC, established under the Australian Government's Cooperative Research Centres (CRC) Program. The CRC Program supports industry-led collaborations between industry, researchers and the community.