Despite the negative effects on older adults, resident-to-resident aggression (RRA) remains a complex and understudied problem. Few interventions exist that address this issue by promoting goodwill. Using the intervention mapping approach, the evaluation of the test phase of the pilot Program GIFT in private seniors’ residences (PSRs) (Quebec, Canada) was conducted through qualitative interviews with 25 residents, 21 staff members, and 4 managers. The results indicate that the program achieved its objectives of promoting goodwill, although the strategies to manage RRA and intervention tools were more difficult to integrate into the PSRs’ culture. Obstacles and facilitators were reported. Recommendations were identified to enhance the program’s content, promote it more effectively, and ensure long-term sustainability. This research is the first endeavour to develop, test, and evaluate the test phase of a pilot program co-created with residents, staff members and managers of PSRs, aiming simultaneously at promoting goodwill and countering RRA.