There is a significant lack of evidence regarding optimum models for service provision in young onset dementia (YOD). Our study aim was to gather detailed information about services experienced as helpful by those with YOD and family carers. The objective was to identify the core features of these services to inform service design, delivery and improvements. A qualitative approach based on appreciative inquiry was used, posing open-ended questions about services experienced as helpful, as part of a national UK survey of people with YOD and carers. We used inductive thematic analysis to analyse the free-text responses. The resulting template was used as a basis for analysis of in-depth follow-up interviews, conducted to acquire greater in-depth understanding. Two hundred and thirty-three survey respondents provided 856 examples of helpful support. Twenty-four follow-up interviews were conducted (two with dyads, so 26 participants in total: 8 with people with YOD, 14 with carers, 2 with dyads). Twelve themes capturing the features of helpful services were clustered into three super-ordinate themes. 'Person-centredness' reflects micro levels of person-professional interaction (positive attitude, flexibility, collaborative, user-friendly materials, and in-person). 'Functional consistency' captures the meso level, demonstrating that services were helpful when organised consistently with needs (age-appropriate, holistic, responsive, and accessible). 'Organisational coherence', at the macro level, emphasises the need for service integration, specialist services and service continuity. Key conclusions are that the needs for flexibility and a collaborative stance may be particularly important for those under 65 years with dementia, who have full lives and are used to being in control; to be age-appropriate, helpful services need to provide activities and opportunities suitable for active middle-aged people; and to be holistic, services need to provide for needs associated with rare dementias and be family-centred. Specialist services need to be commissioned and arrangements need to be stable over time to enable continuity.