ABSTRACTBackgroundA theoretically informed process evaluation was undertaken in parallel to a study examining the feasibility of an oral health intervention based on an existing guideline for care homes. The objectives were to explore the factors that influenced the implementation of the intervention in order to understand the potential pathway to impact. The research team initially utilised Pfadenhauer et al.'s framework, which focuses on a number of different implementation factors: intervention characteristics, context, theory, process, strategy, agents, outcomes and setting.MethodsNine semi‐structured interviews were undertaken with care home managers and staff, predominantly within the intervention arm of the study. Interview schedules were originally based on Pfadenhauer et al.'s framework. These were coded and analysed using thematic analysis. Given the range of themes that emerged, the research team ran a reflexive workshop to determine whether Pfadenhauer et al.'s framework was able to capture and frame the authentic voice of those interviewed.ResultsThe research team found that a systems lens approach better fitted the data from the interviews, capturing the idiosyncrasy of the different settings and the importance of values and beliefs of the key stakeholders. It was clear that unlike the structure proposed by Pfaednhauer et al., many of the factors were interdependent and hierarchical in nature, that is, paradigm and goals within the care home had a direct impact on the system structure, which fed into how the care home was maintained, which led onto how the different actors (care home managers and staff) behaved. The process also highlighted key factors for intervention delivery: time poverty, competing needs, staff turnover, differences between shift patterns and between permanent and agency staff. Cognitive capacity of the residents and staff attitudes were also key.ConclusionsAdding a reflexive workshop enabled the research to critically review the Pfadenhauer et al.'s framework and change to a systems lens approach, which better explained the interdependent and hierarchical nature of the findings. It also highlighted a number of key factors that could influence the pathway to impact for the intervention.Trial RegistrationISRCTN10276613