![enter image description here][1] Over the course of a decade, implement SWATs aims to increase the use of evidence-based strategies for recruiting and retaining participants in randomised trials. Our ambition is for more people to participate in trials, speeding up evidence for health treatments and reducing research waste. **What is the aim of implement SWATs?** Our aim is to promote the use of research evidence for recruiting and retaining participants in randomised controlled trials. To do this, we will: 1. Test the effectiveness and cost-effectiveness recruitment and retention strategies by undertaking coordinated SWATs across different host trials and patient groups at the same time. 2. Develop, implement, and test guidelines for evidence-based recruitment and retention in trials. **What is a SWAT?** A SWAT is a self-contained study that is embedded inside a ‘host’ trial. Randomised SWATs are essential for testing the effectiveness of strategies for recruiting or retaining participants in trials. SWATs can be built into an individual host trial. They can also be built into several host trials at the same time to test how effective a recruitment or retention strategy is across the trials: these are called ‘simultaneous’ or ‘coordinated’ SWATs, and are very powerful as they can produce rapid, high-quality evidence at scale. **What is implementation science?** Implementation science is the study of methods to promote the use of research findings. Implement SWATs is using implementation science to promote the uptake of evidence-based recruitment and retention practice. **Why are we doing implement SWATs?** Trials are effective for testing treatments, but almost half of them fail to recruit enough participants, and many of those who do take part drop out. This causes significant research waste, and delays in providing effective treatments to patients while harmful treatments continue to be used. SWATs are a good way to test recruitment and retention strategies, but few have been done, and there are almost no effective or cost-efficient strategies. Researchers often fail to use evidence when planning recruitment and retention, likely due to a lack of evidence and guidelines. More evidence is needed, along with guidelines and support, to ensure effective recruitment and retention strategies are used, and ineffective ones are avoided. **What methods are we using?** IMPLEMENT SWATs is a multi-methods programme and consists of five interlinked work-packages 1. Identify and prioritise routinely used and most promising recruitment and retention strategies. 2. Undertake simultaneous SWATs of the highest priority recruitment and retention strategies. 3. Develop guidelines for evidence-based, cost-effective trial recruitment and retention. 4. Develop and action a guideline implementation strategy. 5. Evaluate the effectiveness, cost-effectiveness, alongside a process evaluation of the guidelines and implementation strategy. **Funding statement and disclaimer** Implement SWATs is Sponsored by the University of York (UK) and funded by the National Institute for Health and Care Research (Dr Adwoa Parker's Advanced Fellowship, reference: NIHR302256). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. More about the Implement SWATs project is available here: https://www.implementswats.org/ [1]: https://www.implementswats.org/img/implement-logo-1000w.png