The pre-Ga?gesa Navya-Nyaya treatise Upadhidarpa?a (UD) deals with the upadhi, a key concept in the Navya-Nyaya theory of inference. This volume is the first published edition and translation of the only manuscript of the UD. Notes have been added to elucidate the historical context of the authors, works, and philosophical doctrines in the UD.