The Upanisads have often been treated as a unified corpus of religious and philosophical texts, separate from the older Vedic tradition. It is well known that the Upanisads were initially composed and transmitted within specific schools of Vedic recitation, or Sakhas, but the Sakha affiliation of each Upanisad has received very little attention in the scholarly literature. The author offers a new interpretation of the older Upanisads in the light of the Vedic school affiliations of each text. This book argues that issues of textual authority, and in particular the authority of the various Vedic schools, are central in the Upanisads, and that the Upanisads can, on one level, be read as texts about text. While analyzing the theme of textual authority in the Upanisads, the author also outlines a theory of textual criticism as applied to orally transmitted texts that will be of use to textual scholars in other fields as well.