A serious strategic approach is needed, with participants as respected partners “Bah humbug! Sending Christmas cards to trial participants does not increase retention.” So conclude Coleman and colleagues in their linked study of nearly 1500 participants in eight different trials https://www.bmj.com/content/375/bmj-2021-067742 Recruiting and retaining participants is a central preoccupation for clinical research. Would we expect Christmas cards to make a difference?