MEETINGDEM investigated whether the Dutch Meeting Centres Support Programme (MCSP) could be implemented in Italy, Poland, and the UK with comparable benefits. This paper reports on the impact on people living with dementia attending pilot Meeting Centres in the 3 countries. Nine pilot Meeting Centres (MCs) participated (Italy-5, Poland-2, UK-2). Effectiveness of MCSP was compared with Usual Care (UC) on outcomes measuring behavioural and psychological symptoms (NPI), depression (CSDD), and quality of life (DQoL, QOL-AD), analysed by ANCOVAs in a 6-month pre-test/post-test controlled trial. Pre/post data were collected for 85 people with dementia and 93 carers (MCSP) and 74 people with dementia /carer dyads' receiving UC. MCSP showed significant positive effects for DQoL Self-esteem (F = 4.8, P = 0.03); Positive Affect (F = 14.93, P < 0.00); Feelings of Belonging (F = 7.77, P = 0.01) with medium and large effect sizes. Higher attendance levels correlated with greater neuropsychiatric symptom reduction (rho = 0.24, P = 0.03) and a greater increase in feelings of support (rho = 0.36, P = 0.001). MCSPs showed significant wellbeing and health benefits compared with UC, building on the evidence of effectiveness from the Netherlands. In addition to the previously reported successful implementation of MCSP in Italy, Poland, and the UK, these findings suggest that further international dissemination of MCSP is recommended.