Background:
Peer support interventions can improve carer wellbeing and interventions that engage both the carer and person with dementia can have significant mutual benefits. Existing research has been criticised for inadequate rigour of design or reporting. This paper describes the protocol for a complex trial that evaluates one-to-one peer support and a group reminiscence programme, both separately and together, in a factorial design.DesignA 2×2 factorial multi-site randomised controlled trial of individual peer support and group reminiscence interventions for family carers and people with dementia in community settings in England, addressing both effectiveness and cost-effectiveness.DiscussionThe methods described in this protocol have implications for research into psychosocial interventions, particularly complex interventions seeking to test both individual and group approaches.Trial Registration: ISRCTN37956201