BACKGROUND: Facilitation is a widely used implementation method in quality improvement. Reviews reveal a variety of understandings of facilitation and facilitator roles. Research suggests that facilitation interventions should be flexible and tailored to the needs and circumstances of the receiving organisations. The complexity of the facilitation field and diversity of potential facilitator roles fosters a need to investigate in detail how facilitation is enacted. Hence, the purpose of this study was to explore the enactment of external peer facilitation in general practice in order to create a stronger basis for discussing and refining facilitation as an implementation method. METHODS: The facilitation intervention under study was conducted in general practice in the Capital Region of Denmark in order to support an overall strategy for implementing chronic disease management programmes. We observed 30 facilitation visits in 13 practice settings and had interviews and focus groups with facilitators. We applied an explorative approach in data collection and analysis, and conducted an inductive thematic analysis. RESULTS: The facilitators mainly enacted four facilitator roles: teacher, super user, peer and process manager. Thus, apart from trying to keep the process structured and focused the facilitators were engaged in didactic presentations and hands-on learning as they tried to pass on factual information and experienced based knowledge as well as their own enthusiasm towards implementing practice changes. While occasional challenges were observed with enacting these roles, more importantly we found that a coaching based role which was also envisioned in the intervention design was only sparsely enacted meaning that the facilitators did not enable substantial internal group discussions during their facilitation visits. CONCLUSION: Facilitation is a complex phenomenon both conceptually and in practice. This study complements existing research by showing how facilitation can be enacted in various ways and by suggesting that some facilitator roles are more likely to be enacted than others, depending on the context and intervention design and the professional background of the facilitators. This complexity requires caution when comparing and evaluating facilitation studies and highlights a need for precision and clarity about goals, roles, and competences when designing, conducting, and reporting facilitation interventions.