Post-diagnostic care in young-onset dementia (YoD) varies, from something that is occasionally structured, to improvised, to frequently non-existent depending on geographic region. In a few regions in England, a nurse designated to helping families may exist. This study aimed to describe this seldom-observed nursing role and its content. It used an investigative qualitative case study design based on the analysis of two YoD clinical nurse specialists (CNSs) describing the work they did in providing post-diagnostic care to YoD service users. The CNSs address various areas affected by mid-life dementia, including patients’ mental health, caregiver stress and families’ psycho-social problems. They use various approaches in delivering care, including making home visits, acting as a personal contact for service users and liaising with other health and social care services. Desirable attributes of a CNS service include service users having access to the same CNS throughout their care, receiving timely care and experiencing longer-term support and reassurance. In the post-diagnostic period, service user needs are often more psycho-social than medical, and the CNS role can complement and add value to clinical appointments. The role allows service users to be managed in the community, to receive information, guidance and advice and can prevent and de-escalate problems.