Introduction: Research into young onset dementia (YOD) tends to focus on the experience from the perspective of the person with the condition or that of their primary carer, typically a spouse or partner. However, many people diagnosed with YOD are part of a wider family system that may include children, yet the experiences of children are consistently absent from the literature. The aim of this research was to investigate the impact of parental YOD on the family system with specific emphasis on the experiences of children and young adults in an Irish context. Methods: A qualitative research approach was utilised that allowed the exploration of the attitudes, opinions, behaviours and interactions of individuals taking account of the environment in which they occur. Firstly, participatory workshops with members of the Alzheimer Society of Ireland (ASI) Dementia Research Advisory Team (DRAT) were conducted. Members of DRAT are people living with YOD residing in the community. The participatory workshops assisted in the development of research topics of relevance to people living with YOD and their families and guided the research questions addressed in this thesis. Stemming from the participatory workshops, a qualitative systematic literature review was conducted to synthesise the relevant literature in relation to children and young adults experiences of parental YOD. Following this, individual studies employed focus group and one-to-one semi structured interviews with family members including people with YOD (n = 13), spouses/partners (n = 25) and children (n = 36). Data were analysed using thematic analysis in order to recognise, analyse, detail and describe recurring patterns, underpinned by the theoretical framework of Family Systems Theory and Cultural Transmission Theory. Findings: Across the individual studies, participants reported being significantly impacted by parental YOD leading to considerable adversity. Children and young adults outlined how parental YOD has led to pronounced challenges such as learning to adapt to a new and arduous situation. Consequently, participants reported heighten levels of fear, anxiety, anger, guilt, shame and loneliness. Additionally, the stereotypical view of dementia combined with the general lack of awareness and understanding about YOD can lead to pronounced stigma both at a familial and societal level. Participants highlighted the difficulties when attempting to access formal health and social care support, citing the lack of service provision for younger people combined with poor communication with providers. Furthermore, due to stigma, many children and young adults do not turn to friends for psycho-social support, relying instead on their “well parent” putting a further strain on the family system. Conclusion: Children and young adults with a parent with YOD face significant and unique challenges and therefore require unique psycho-social support(s). However, support must be tailored and stratified by age as one size may not fit all. Any intervention must be a collaborative approach between children and health care providers, with substantial input from children at all stages. Peer-to-peer support is presented as a possible intervention. Peer support has been shown to be an effective tool in the area of youth mental health and as a psycho-social support for children facing other serious parental illnesses. Combined with education and awareness programmes, peer-to-peer support may assist children and young adults facing parental YOD.