Catherine began her rule with great projects of reform. She drew up a document, based largely on the writings of Beccaria and Montesquieu, to serve as a guide for an enlightened code of laws. She summoned a legislative commission (with representatives of all classes except the serfs) to put this guide into law, but she disbanded the commission before it could complete the code. Some have questioned the sincerity of Catherine's "enlightened" outlook, and there is no doubt that she became more conservative as a result of the peasant rising (1773–74) under Pugachev.

The nobility's administrative power was strengthened when Catherine reorganized (1775) the provincial administration to increase the central government's control over rural areas. This reform established a system of provinces, subdivided into districts, that endured until 1917. In 1785, Catherine issued a charter that made the gentry of each district and province a legal body with the right to petition the throne, freed nobles from taxation and state service and made their status hereditary, and gave them absolute control over their lands and peasants. Another charter, issued to the towns, proved of little value to them. Catherine extended serfdom to parts of Ukraine and transferred large tracts of state land to favored nobles. The serfs' remaining rights were strictly curtailed. She also encouraged colonization of Alaska and of areas gained by conquest. She increased Russian control over the Baltic provinces and Ukraine.

Catherine attempted to increase Russia's power at the expense of its weaker neighbors, Poland and the Ottoman Empire. In 1764 she established a virtual protectorate over Poland by placing her former lover Stanislaus Poniatowski on the Polish throne as Stanislaus II. Catherine eventually secured the largest portion in successive partitions of Poland among Russia, Prussia, and Austria (see Poland, partitions of).

Catherine's first war with the Ottoman Empire (1768–74; see Russo-Turkish Wars) ended with the Treaty of Kuchuk Kainarji, which made Russia the dominant power in the Middle East. Catherine and her advisers, particularly Potemkin, developed a program known as the Greek Project, which aimed at a partition of the Ottoman Empire's European holdings among Russia, Austria, and other countries. However, her attempts to break up the Ottoman Empire met with limited success. In 1783 she annexed the Crimea, which had gained independence from the Ottoman Empire by the Treaty of Kuchuk Kainarji. Her triumphal tour of S Russia, accompanied by Potemkin, provoked the Ottomans to renew warfare (1787–92). The Treaty of Jassy (1792) confirmed the annexation of the Crimea and cemented Russia's hold on the northern coast of the Black Sea.

Catherine also extended Russian influence in European affairs. In 1778 she acted as mediator between Prussia and Austria in the War of the Bavarian Succession, and in 1780 she organized a league to defend neutral shipping from attacks by Great Britain, which was then engaged in the war of the American Revolution.

Catherine increased the power and prestige of Russia by skillful diplomacy and by extending Russia's western boundary into the heart of central Europe. An enthusiastic patron of literature, art, and education, Catherine wrote memoirs, comedies, and stories, and corresponded with the French Encyclopedists, including Voltaire, Diderot, and d'Alembert (who were largely responsible for her glorious contemporary reputation). She encouraged some criticism and discussion of social and political problems until the French Revolution made her an outspoken conservative and turned her against all who dared criticize her regime. Although she had many lovers, only Orlov, Potemkin, and P. L. Zubov (1767–1822) were influential in government affairs. She was succeeded by her son Paul I.

See biographies by H. Troyat (1984) and J. T. Alexander (1989); study by I. DeMadariaga (1982).