This chapter argues that Thai manners today, although expressed in secular terms, contain vestiges of an older Buddhist theory of how to master the self. This theory, which is based on well-known Buddhist scripture as well as monastic and lay practice, places importance on training oneself to restrain one's body (kai), one’s speech (waja), and the mind (jai). Ideals of Buddhist conduct in the Theravada Buddhist world are often associated with the stories of the bodhisatta, the future Buddha, particularly through the Jataka tales. However, Buddhist scriptures also prescribe ideal forms of behaviour for the bourgeois 'householder', especially in the Sigalovada Sutta, which was popular throughout the Theravada Buddhist world. The chapter situates these discourses of good conduct within Thai history in the nineteenth century, when political, economic, and social changes were producing a more bourgeois society, albeit within the political framework of a traditional absolute monarchy.