Background: In the MEETINGDEM project, the Meeting Centers Support Program (MCSP) was adaptively implemented and evaluated in three European countries: Italy, Poland, and the United Kingdom. The aim of this study was to investigate overall and country-specific facilitators and barriers to the implementation of MCSP in these European countries.; Methods: A qualitative multiple case study design was used. Based on the theoretical model of adaptive implementation, a checklist was composed of potential facilitators and barriers to the implementation of MCSP.