Rationale The majority of stroke patients are discharged home dependent on informal caregivers, usually family members, to provide assistance with activities of daily living, including bathing, dressing, and toileting. Many caregivers feel unprepared for this role, and this may have a detrimental effect on both the patient and caregiver. Aims To evaluate whether a structured, competency-based training programme for caregivers improves physical and psychological outcomes for patients and their caregivers after disabling stroke, and to determine if such a training programme is cost-effective. Design A cluster randomized controlled trial. The trial aims to recruit 25 patient and caregiver dyads from each of the 36 participating stroke rehabilitation units. Stroke units have been randomized to either the intervention or control group with randomization stratified by geographical region and quality of care. The intervention is the London Stroke Carer Training Course developed and evaluated in a previous single-centre study. The London Stroke Carer Training Course comprises a number of caregiver training sessions and competency assessment delivered while the patient is in the hospital and one follow-up session after discharge. The multidisciplinary teams in the units randomized to the intervention group have been trained to incorporate delivery of the London Stroke Carer Training Course into ward practice, while those randomized to the control group have continued to provide usual care according to national guidelines. Study outcomes The primary outcomes are extended activities of daily living for the patient and caregiver burden measured at six-months after recruitment. Secondary outcomes include mood and cost-effectiveness, with final follow-up at 12 months.