Background: There is a need to better understand the experiences and support needs of paid and family carers of people with an intellectual disability and dementia, and the role of Intellectual Disability Dementia Care Pathways (IDDCPs). This study explored the experiences of carers, and IDDCPs and other support structures within those experiences. Methods: A constructivist grounded theory methodology was implemented. Data were obtained through 23 semi-structured interviews with two family carers, eight paid carers and eight healthcare professionals. Findings: The study's theory produced five interrelated categories: Impact of Dementia, Challenging the Diagnosis Process, Continuum of Support, Continuity and Continuum of Understanding. Conclusions: Findings have demonstrated the importance of planning and supporting carers' holistic needs; the role of an IDDCP in the post-diagnostic support (or lack of it) for carers; and the importance of a timely diagnosis of dementia. Recommendations for practice are offered.