Lay summaries are critical for building publictrust in clinical research and therefore forrecruiting patients. They are also an importantpart of efforts to improve data transparency.Due to new global regulations, lay summarieswill soon probably become mandatory for allclinical studies. Medical writers shouldtherefore be aware of the regulations andessential content of lay summaries. Using acase study of a published lay summary, thisarticle discusses best practices, including theappropriate target audience, language, anddata and visual presentation.