was born in Stettin, at that time a recovering war-ravaged port city in the Prussian Province of Pomerania (and since 1945 a Polish city known internationally by its Polish-language name as Szczecin). He was the third son of Ernst Wilhelm von Schlabrendorf by his marriage to Anna Carolina von Otterstaedt, from the aristocratic . The two families had been close for a number of generations. Soon after Gustav's birth, his father was appointed First Minister of Silesia. As a result of the promotion the family moved, in 1755, to the Silesian capital, Breslau (as Wrocław was known at that time). The job of integrating the prosperous and recently annexed Silesian territories into the Kingdom of Prussia was a major challenge, but it was one for which Ernst Wilhelm von Schlabrendorf was apparently well rewarded in various ways. On 20 March 1763 the king made him a special gift of 50,000 Thalers. By the time he died in 1769 his family was, by the standards of the time and place, conspicuously wealthy. Gustav von Schlabrendorf spent most of his childhood in Silesia. He received a thorough and comprehensive schooling from and then, in 1767, moved on to Hochschule (university) level education in Frankfurt am Oder where he remained till 1769. Between 1769 and 1772 he continued his studies at Halle. He had enrolled to study Law, which would have provided a conventional preparation for a career in public administration. Gustav von Schlabrendorf, however, interpreted his curricular opportunities more widely, studying ancient and Modern Languages along with Philosophy and the Arts. He was also drawn to Freemasonry which had arrived in Prussia from England and Scotland earlier that century. In 1777 he was accepted into the lodge in Leipzig.