Introduction Better understanding of patient experience is an important driver for service improvements and can act as a lever for system change. In the United Kingdom, the patient experience is now a central issue for the National Health Service Commissioning Board, clinical commissioning groups and the providers they commission from. Traditionally, dementia care in the United Kingdom has focused predominantly on the individual experience of those with late onset dementia, while the voice of those with young onset dementia has been, comparatively, unheard. This study aims to improve the understanding of the personal experience of younger people undergoing investigation for dementia. Methods A modified Delphi approach was undertaken with 18 younger people with dementia and 18 supporters of people with young onset dementia. Questions were informed by a scoping review of the literature (O’Malley, M., Carter, J., Stamou, V., Lafontaine, J., & Parkes, J. (2019a). Receiving a diagnosis of young onset dementia: A scoping review of lived experiences. Ageing & Mental Health, 0(0), 1-12). Summary individual statements were refined over two rounds to a final list of 29 key statements. Results Twenty-seven of these statements were rated as absolutely essential or very important and included (1) for the general practitioner to identify dementia in younger people, (2) clinicians should be compassionate, empathic and respectful during the assessment and particularly sensitive when providing information about a diagnosis, and (3) remembering that receiving the diagnosis is a lot to absorb for a person with dementia and their supporter. Statistical analyses found no difference in the scoring patterns between younger people with dementia and supporters, suggesting similar shared experiences during the diagnostic process. Conclusion Understanding the uniquely personal experience of young people going through the process of diagnosis for dementia is essential to provide person-centred, needs-led, and cost-effective services. Patient’s values and experiences should be used to support and guide clinical decision-making.