BACKGROUND: Improving care at home for people with dementia is a core policy goal in the dementia strategies of many European countries. A challenge to effective home support is the occurrence of crises in the care of people with dementia which arise from changes in their health and social circumstances. Improving the management of these crises may prevent hospital admissions and facilitate better and longer care at home. This trial is part of a National Institute for Health Research funded programme, AQUEDUCT, which aims to improve the quality and effectiveness of teams working to manage crises in dementia. METHODS/DESIGN: It is a pragmatic randomised controlled trial of an online Resource Kit to enhance practice in teams managing crises in dementia care. Thirty teams managing mental health crises in dementia in community settings will be randomised between the Resource Kit intervention and treatment as usual. The primary outcome measure is psychiatric admissions to hospital for people with dementia in the teams' catchment area recorded 6 months after randomisation. Other outcomes include quality of life measures for people with dementia and their carers, practitioner impact measures, acute hospital admissions and costs. To enhance understanding of the Resource Kit intervention, qualitative work will explore staff, patient and carers' experience. DISCUSSION: The Resource Kit intervention reflects current policy to enable home-based care for people with dementia by addressing the management of crises which threaten the viability of care at home. It is based upon a model of best practice for managing crises in dementia designed to enhance the quality of care, developed in partnership with people with dementia, carers and practitioners. If the Resource Kit is shown to be clinically and cost-effective in this study, this will enhance the probability of its incorporation into mainstream practice. TRIAL REGISTRATION: ISRCTN 42855694 ; Registered on 04/03/2021; Protocol number: 127686/2020v9; Research Ethics Committee, 09/03/2021, Ref 21/WM/0004; IRAS ID: 289982.