BackgroundTrial method research produces recommendations on how to best conduct trials. However, findings are not routinely implemented into practice. To better understand why, we conducted a mixed method study on the challenges of implementing trial method research findings into UK-based clinical trial units.MethodsThree stages of research were conducted. Firstly, case studies of completed projects that provided methodological recommendations were identified within trial design, conduct, analysis, and reporting. These case studies were used as survey examples to query obstacles and facilitators to implementing method research. Survey participants were experienced trial staff, identified via email invitations to UK clinical trial units. This survey assessed the case studies’ rates of implementation, and demographic characteristics of trial units through the Consolidated Framework for Implementation Research. Further, interviews were conducted with senior members of trial units to explore obstacles and facilitators in more detail. Participants were sampled from trial units that indicated their willingness to participate in interviews following the survey. Interviews, and analysis, were structured via the Capability, Opportunity, Motivation Model of Behaviour. Finally, potential strategies to leverage lessons learned were generated via the Behaviour Change Wheel.ResultsA total of 27 UK trial units responded to the survey. The rates of implementation across the case studies varied, with most trial units implementing recommendations in trial conduct and only few implementing recommendations in reporting. However, most reported implementing recommendations was important but that they lacked the resources to do so. A total of 16 senior members of trial units were interviewed. Several themes were generated from interviews and fell broadly into categories related to the methods recommendations themselves, the trial units, or external factors affecting implementation. Belief statements within themes indicated resources issues and awareness of recommendations as frequent implementation obstacles. Participation in trial networks and recommendations packaged with relevant resources were cited frequently as implementation facilitators. These obstacles and facilitators mirrored results from the survey. Results were mapped, via the Behaviour Change Wheel, to intervention functions likely to change behaviours of obstacles and facilitators identified. These intervention functions were developed into potential solutions to reduce obstacles and enhance facilitators to implementation.ConclusionsSeveral key areas affecting implementation of trial method recommendations were identified. Potential methods to enhance facilitators and reduce obstacles are suggested. Future research is needed to refine these methods and assess their feasibility and acceptability.