As the number of people living with dementia is increasing globally, Dementia Friendly Communities (DFCs) offer one way of providing the infrastructure and support that can enable people affected by dementia to live well. There is no universally agreed definition of a DFC, and DFCs need not be geographical entities. This study adopted a broad definition, recognising that becoming a DFC is an ongoing process only fully achieved when living with dementia is normalised into a community’s culture, language, infrastructure and activities. A DFC can involve a wide range of people, organisations and geographical areas. A DFC recognises that a person with dementia is more than their diagnosis and that everyone has a role in supporting their independence and inclusion. DFCs in England can apply for official recognition by Alzheimer’s Society as working towards dementia friendly status. A growing number of national and international frameworks and guidance is available to communities seeking to become dementia friendly. Evaluations of DFCs are largely descriptive. While work exists on identifying core outcomes of DFC initiatives, there are very few studies that have tested DFC effectiveness or compared current practice with known need. Evidence on cost effectiveness, cost benefit, social value and social return on investment (SRoI) of DFCs is also missing. This study addresses key gaps in the evidence.