Background and objectives: Although randomized controlled trials (RCTs) have been performed to alleviate loneliness among older people, little is known about how they have been implemented, or whether they are effective in real life. Our RCT-based model, "Circle of Friends" (CoF) proved to be effective in improving the wellbeing, health and cognition of lonely older people. Over 10 years we have systematically trained 752 professional facilitators of lonely older people's CoF groups. This study aims to explain how this training has succeeded in practice and to describe the outcomes of CoF implementation. Research Design and Methods: Survey data were gathered in 2006-2016 from trained facilitators (n = 319) and CoF participants (n = 1041). Results: The CoF has been disseminated in 80 municipalities in Finland. The trained CoF facilitators have maintained the original key elements and structure of the model fairly well in its implementation and dissemination processes. The main objectives of CoF--the alleviation of loneliness, making new friends, and members continuing meetings on their own--have remained the facilitators' priority. The CoF socially activates older participants, as 67% organized group meetings after the facilitated process. However, the CoF has become diluted in some aspects during its dissemination, as a small proportion of trained facilitators have implemented the model in their own way. Discussion and Implications: The CoF may be an encouraging example of how an original RCT model with a rigorous training program can be implemented and disseminated in real-life settings over 10 years.