On 20^th May 2020 we mark International Clinical Trials Day, an opportunity to recognize the people who carry out clinical trials and thank them for their efforts in improving public health. This of course includes the patients who participate in those trials, without whom the trials simply would not happen. It also includes the patient and public contributors who can shape the trials, helping to ensure they address questions of importance and relevance for patients, as well as being practical and feasible to run.

Internationally, public involvement is becoming embedded within the design and conduct of trials and is increasingly seen as usual practice. This reflects the many ethical, moral and political arguments for involving patients and members of the public in research, as well as the argument that such involvement can enhance the quality of the research (Staniszewska et al., 2018). Ensuring that the outcomes a trial measures are important to patients can help to develop the relevance of a trial, and so enhance the potential health benefits it will create for patients by ensuring the intervention is evaluated against what really matters for patients. Public involvement in trials can also help retention of participants, as recruitment strategies and the design of trials aligns with the reality of peoples’ lives, helping to ensure that participation is desired and feasible, and promoting the concept that a clinical trial is a treatment option for patients and is intended to benefit patients, whether now or in the future.

In developing our international approach to public involvement in trials, we view involvement as an area of evidence-based social practice. This means that when we plan and undertake public involvement in trials, we should draw on evidence of what works, for whom, why and in what context.

If we don’t use available evidence of what works in public involvement, it is a form of research waste, as it misses opportunities to create the highest quality clinical trials.

If we don’t have the evidence of what works best in public involvement in a specific aspect of clinical trial development, we need to actively develop and publish it, to ensure our international community can learn from it – including the public and patients.

Our journal, Research Involvement and Engagement, is dedicated to developing the evidence base to inform the practice of patient and public involvement. We have published a wide range of papers focusing on different aspects of involvement in trials. These include papers focused on key aspects of trial delivery such as the development of online portals for recruitment (Markham, 2016), how to involve people in the design and conduct of trials (Batten et al., 2018), the development of a toolkit to support PPI in trials (Bagley et al., 2016) and co-production for feasibility and pilot randomised trial (McConnell et al., 2018). In addition, we have published papers that tackle the challenges of involving seldom-heard groups (Rayment et al., 2017; Morgan et al., 2016), and key issues such as the need to place patient-important outcomes centre stage in trials (Selby and Velikova, 2018; Smith et al., 2018; Wilson 2018) and the need to understand the motivations and expectations of those involved in trials (Schilling et al. 2019, Estacourt et al., 2016).  There is also a recent paper on involving participants and community groups in trial design and delivery (Gafos et al., 2020) and even a letter from a medical student on “discovering” public involvement in trials (Lewis, 2020).

Our published studies and those published by our sister journals, provide an important and growing evidence base, on which we draw when planning and undertaking public involvement in trials. Blended with the tacit knowledge of researchers and clinicians, we have the potential to create high quality, relevant and appropriate clinical studies. As we move forward in the design and delivery of trials, and in disseminating their results and benefits, embedded high-quality public involvement in all aspects of trial design will increasingly become the norm. As we celebrate Clinical Trials Day, we give thanks to all the participants, researchers, clinicians and public contributors who have given so much to help advance the science and art of clinical trials and create international improvements in health.