Psychosocial intervention makes a vital contribution to dementia care. However, the lack of consensus about which outcome measures to use to evaluate effectiveness prevents meaningful comparisons between different studies and interventions. This study used an iterative collaborative, evidence-based approach to identify the best of currently available outcome measures for European psychosocial intervention research. This included consensus workshops, a web-based pan-European consultation and a systematic literature review and a rigorous evaluation against agreed criteria looking at utility across Europe, feasibility and psychometric properties. For people with dementia the measures covered the domains of quality of life, mood, global function, behaviour and daily living skills. Family carer domains included mood and burden, which incorporated coping with behaviour and quality of life. The only specific staff domain identified was morale, but this included satisfaction and coping with behaviour. In conclusion twenty-two measures across nine domains were recommended in order to improve the comparability of intervention studies in Europe. Areas were identified where improved outcome measures for psychosocial intervention research studies are required.