Works of Sthiramati, a Yogacara thinker, exist in Sanskrit, Chinese, and Tibetan. A portion of his thought is also conveyed in Cheng wei shi Lun. Until now, Sthiramati's thought has been primarily understood as it is presented in Cheng wei shi Lun, and accordingly, he has been regarded as a nirakarajnanavadin. An examination of other works of his in Sanskrit and Tibetan, however, does not necessarily support such an interpretation. While focussing mainly on the Tri-svabhava doctrine, this paper reexamines Sthiramati's thought as it is presented in Cheng wei shi Lun, and seeks to evaluate the consistency and truth of that position. Sthiramati's Tri-svabhava doctrine does not equate the objective part of vijnapti with parikalpita-svabhava, nor the subjective part of vijnapti with paratantra-svabhava. Rather, the subjective part and the objective part of vijnapti are together associated with palikalpita-svabhava, while the substantial part of vijnapti associated with paratantra-svabhava. This classification is applied even to the prsthalabdhajnana of Bodhisattvas, only Buddhas being excepted from it. It is on the basis of this dualistic division within parikalpita-svabhava that the substantiality of self and things is provisionally established in language. These issues are examined in detail in this paper. This position, however, does not coincide well with many early texts of the Yogacara school, such as Yogacarabhumi or Mahayanasamgraha. Most probably, the position attributed to Sthiramati in Cheng wei shi lun is not the position of the real Sthiramati, as found in his works preserved in Sanskrit and Tibetan. The position presented in Cheng wei shi lun is actually quite peculiar from the perspective of the philosophical history of the Yogacara school, and seems to be lacking in logical consistency.