Objectives: Internet-delivered psychological interventions can be regarded as evidence-based practices and have been implemented in psychiatric and somatic care at primary and specialist levels. However, challenges as low adherence and poor routinization, have arisen during attempts to implement internet-delivered interventions in chronic pain settings. Internet-delivered Acceptance and Commitment Therapy (IACT) has been found to be helpful for chronic pain patients and might aid in developing pain rehabilitation services. However, the integration of IACT into standard health care has not yet been described from an implementation science perspective. The aim of this hybrid 1 effectiveness-implementation study was to evaluate the process of implementing IACT in a pain rehabilitation setting, to guide future implementation initiatives.Methods: In this retrospective study we described actions taken during an implementation initiative, in which IACT was delivered as part of an interdisciplinary pain rehabilitation program (IPRP) at a specialist level clinic. All documents relevant to the study were reviewed and coded using the Quality Improvement Framework (QIF), focusing on adoption, appropriateness and sustainability.Results: The QIF-analysis of implementation actions resulted in two categories: facilitators and challenges for implementation. Sustainability may be facilitated by sensitivity to the changing needs of a clinical setting and challenged by unfitting capacity building. Appropriateness might be challenged by an insufficient needs assessment and facilitated by aligning routines for communication with the clinics existing infrastructure. Adoption may be facilitated by staff key champions and an ability to adapt to occurring hurdles. Possible influential factors, hypotheses and key process challenges are presented in a logic model to guide future initiatives.Conclusions: Sustainable implementation may depend on both the continuity of facilitating implementation actions and flexibility to the changing needs and interests of patients, caregivers and organization. We conclude that the use of theories, models and frameworks (TMF) as well as a logic model may ease design, planning and evaluation of an implementation process. Lastly, we suggest that IACT may be appropriate for IPRP when given before or after IPRP, focusing on psychiatric comorbidities.