The Svetasvatara Upanisad is not usually considered to be among the ten Upanisads commented on by Samkara. The Upanisad questions the origin of creation, and explores the relationship between the soul and the Supreme Deity, emphasizing the importance of meditation in realising the Deity. The commentary has a long introduction teaching that liberation comes through knowledge, not rites, quoting profusely from the Puranas and other sources. The commentary on the text itself further expands the Keveladvaitavedanta of Samkara's School, inculcating the unity of the Self, which is the real, and the unreality of all else, Gods spoken of, such as Rudra, are taken as referring to the nondual Brahman, and the various means spoken of are interpreted as means of realising Brahman. Whether this commentary is actually the work of Adisamkara has been disputed for over a century. Indeed, the authenticity of many works attributed to Samkara has been called into doubt. In the case of the Svetasvataropanisadbhasya, no thorough-going tests have been applied and published. The present study, by a combination of Hacker's litmus-test of authenticity, and other evidence gleaned, proves fairly conclusively that the commentary is not the work of Adisamkara, but of a later follower, thus vindicating the view that Adisamkara wrote commentaries on only ten Upanisads.