This thesis presents an account of a prominent eighteenth-century European naturalist, Peter Pallas (1741-1811), in the setting to which he contributed his scientific talents—the St. Petersburg Academy of Sciences. A complete outline of Pallas' life is presented for purposes of continuity, but the heart of the thesis is presented in chapters four and five, which combined, relate the major features of Pallas' career in Russia. These two chapters are set against pertinent background material, most of which is involved with the institution itself which supported Pallas. The St. Petersburg Academy of Sciences is surveyed in its origin and development in the eighteenth century and material is presented which will outline the ups and downs of the development of academic life in Russia as well as the general milieu in which Pallas fitted. This milieu, it has been concluded, was one of lively and relatively unfettered advance in the development of science in Russia, to which Pallas contributed a great deal of stimulus by way of his widely known and respected accomplishments. The focal point of Pallas' career is represented by his Siberian expedition of 1768-1774, a momentous six-year scientific enterprise to which a central part of the research has been directed. The account of the Pallas Expedition presented here is entirely original, utilizing chiefly his own travel account and the Proceedings (Protokoly) of the Academy, from which source, in the absence of archival materials, can be gained the general content of Pallas' communications to the Academy during his absence. To add perspective, the Pallas Expedition has been set against the historical and contemporary background of Russian scientific exploration in the eighteenth century. An appendix has also been included which lists the Russian-sponsored eighteenth-century scientific expeditions. The follow-up to Pallas' expedition--the remainder of his career in St. Petersburg--is equally a central part of the study. As an academician in St. Petersburg from 1774 to 1793, Pallas was a luminary of European natural science as well as a pillar of scientific achievement in Russia. In historical terms and seen against the background of the Academy of which he was a part, Pallas’ scholarly contributions in Russia have been outlined, most of which can be explained as a consequence of his expedition. A wide selection of available secondary material has been utilized to explain Pallas’ academic career supplemented by some original research supplemented by some original research (chiefly from the Academy Proceedings) and the opportunity I have had to see and scan most of his major publications pertaining to zoology and botany, the major fields to which he contributed. Although of German background, Pallas spent most of his adult life in Russia (1767-1810). His career there forms one of the highlights of foreign scientific expeditionary achievement during the century that Russia relied almost exclusively on foreigners to establish the serious beginnings of both. His contributions--expeditionary and academically in the realm of biology--for obvious reasons are more closely connected to the Russian arena; perhaps for that reason he has failed to attract deserved notice alongside the eighteenth-century European naturalists who are now more popularly known. This thesis attempts no more than to account historically for the career of Peter Simon Pallas in Russia and to present his remarkable accomplishments. A categorized, partially annotated bibliography is appended, preceded by a bibliographic explanation.