Background: The current mandate in dementia research is to develop interventions that are evidence-based and person-centred. However, person-centred augmentative and alternative communication interventions in dementia are limited. Method: A multimethod research design was conducted in three Phases. Phase one reviewed current research evidence to inform the development of a person-centred intervention. Phase two developed a person-centred augmentative and alternative communication intervention package with four components, (a) elements of person-centred care; (b) an electronic conversational support; (c) augmentative and alternative communication outcomes; and (d) an outcome measure. Phase three tested the feasibility of these four components by considering them in two ways (phase 3A and phase 3B). In 3A, Q-methodology was employed to obtain professionals’ viewpoints. In 3B, a case study was used to test the feasibility of the researcher’s implementation of an electronic conversational support with a participant with dementia and the scoring reliability of an outcome measure developed in this study. Results: Q-methodology results revealed professional views on (i) person-centred authorship, (ii) person-centred language style using supportive strategies (iii) adapted participatory methods with persons with dementia in their interventions. Case study results indicated that an electronic conversational support could be reliably implemented. Inter-rater reliability was not at an acceptable level for the multimodal domain of an outcome measure developed in this study. Conclusion: This study highlights the importance of using person-centred scaffolding strategies and exploring the potential of adapted participatory methods to develop and implement evidence-based, person-centred interventions in persons with dementia.