This book explores the rise of insight meditation (vipassanā) as a widespread lay movement in Burma during British colonial rule. It does this through a study of one of its key architects, the Burmese monk Ledi Sayadaw (1846-1923). His life and work shows that mass meditation emerged out of the relationship between two spheres of action, the study of Buddhist doctrine and the effort to protect the Buddhist religion. In terms of doctrinal study, Ledi empowered a wide range of people to participate in the longstanding elite practice of in-depth study, focusing particularly on the Buddhist philosophical texts, the Abhidhamma. He tied this study to the second sphere, protective efforts, by arguing that such study empowered a person to safeguard Buddhism. He then presented meditation as another way to insure Buddhism’s safety— not to mention as a means to spiritual attainments— and he standardized and simplified meditation methods for lay people using the Abhidhamma. By allying insight practice in this way to study and protection, he set in train the collectivization of practice and the acceptability of lay control of its teaching, now hallmarks of modern Buddhism across the world. This analysis challenges the common assumption that colonialism forced the Burmese to entirely reconceive their traditions, for it shows that Ledi and other Burmese responded to the pressures of colonialism on pre-colonial terms. Thus, in explaining why mass meditation started in Burma, the book also extends into the pre-colonial past our understanding of sources for a form of Buddhist modernity.