Background Agitation in dementia is common, persistent and distressing and can lead to care breakdown. Medication is often ineffective and harmful. Aims To systematically review randomised controlled trial evidence regarding non-pharmacological interventions. Method We reviewed 33 studies fitting predetermined criteria, assessed their validity and calculated standardised effect sizes (SES). Results Person-centred care, communication skills training and adapted dementia care mapping decreased symptomatic and severe agitation in care homes immediately (SES range 0.3–1.8) and for up to 6 months afterwards (SES range 0.2–2.2). Activities and music therapy by protocol (SES range 0.5–0.6) decreased overall agitation and sensory intervention decreased clinically significant agitation immediately. Aromatherapy and light therapy did not demonstrate efficacy. Conclusions There are evidence-based strategies for care homes. Future interventions should focus on consistent and long-term implementation through staff training. Further research is needed for people living in their own homes.