Confronted with warfare and the urgency of spreading Buddhist teachings, in the 12th century the Sinhalese monk Ānanda, himself a refugee in South India, composed a work addressing lay persons. What beliefs and practices define a lay Buddhist, and how do they inform her or his daily life to the point of shaping the relationship between husband and wife or employers and employees? And what beliefs and practices are incompatible with Buddhism? The result, the most detailed treatise on lay followers (upāsaka) handed down by the tradition, is here translated into English in its entirety for the first time. Ānanda marshals an impressive number of otherwise scattered canonical and post-canonical passages, encompassing in nine chapters many aspects of Buddhism, including the philosophically important doctrine of “no-self”, often considered the domain of learned monks because of its subtlety and the unattached outlook it requires on one’s property, life and person.