Aim To evaluate the effect of a targeted community‐based psychosocial intervention on self‐efficacy outcomes for care recipient/carer dyads living with early‐stage dementia. Background There is increasing interest in the role of self‐efficacy and self‐management structures in determining positive outcomes for people with dementia. The assumption is that care recipient/carer dyads who receive early support to identify and adjust to dementia‐related changes will cope better in the long term. Design An explanatory sequential mixed‐method design was employed. Primarily quantitative with qualitative data providing a supportive secondary role to expand on and illuminate the quantitative findings. Methods Eighty‐eight dyads were recruited and allocated on a regional basis to an intervention or control group. Intervention group dyads received the Early Diagnosis Dyadic Intervention. Control group dyads received two information manuals. Quantitative data were collected at three time points. Qualitative data were collected via evaluation questionnaires and semistructured interviews. Results Intervention structure, content, and delivery were acceptable to the dyads but few quantitative self‐efficacy findings reached statistical significance. Improvements in self‐efficacy were evident in the postintervention evaluation qualitative responses where dyads expressed greater confidence in identifying and accessing community support. Conclusion There is an urgent need for effective psychosocial interventions to help reduce the impact of dementia symptoms on patients, carers, and society. This study makes an important contribution to our understanding of the capacity of psychosocial interventions to improve self‐efficacy outcomes for care recipient/carer dyads with early‐stage dementia while also illustrating the challenges associated with measuring self‐efficacy in the early stages of the condition.