In premodern Britain civic officials took oaths in solemn ceremonies in full view of their colleagues and fellow citizens. This article examines oaths ranging from the fourteenth to the seventeenth centuries from 31 towns in England, Scotland, and Ireland to demonstrate how officials were ritually enjoined to keep secrets. Oaths were public acknowledgments that secrets were going to be kept. The act of governing necessitated the keeping of secrets to ensure the protection of the town's interests. But oath-taking was also a concession to the idea that governing required a degree of transparency for the ruling elite and other authorities to appear legitimate and incorruptible.