This case study explored how a researcher-community partnership contributed to program adaptations when implementing person-centered group-based health promotion services to older people who have migrated to Sweden. The study was conducted over 3 years and various data sources were used: focus groups, individual interviews, documents, and archive material. Findings from different data sources and partners' perspectives were triangulated to an overall case description using an iterative process. Adaptations were shaped through a dynamic process, negotiating toward suitable solutions that culminated in actions taken to adapt or inhibit adaptations. The negotiations were driven by the interplay within and between three reasons to adapt. The partners' opportunities to influence the negotiation process depended on establishing common ground to shape adaptations. Practical implications are provided on how to move from knowledge to action when implementing person-centered group-based health promotion to support optimal aging in the context of migration.