The szlachta ([ˈʂlaxta] (About this soundlisten), exonym: Nobility) was a legally privileged noble class in the Kingdom of Poland and in the Grand Duchy of Lithuania. After the Union of Lublin in 1569, the Grand Duchy and its neighbouring Kingdom became a single state, the Polish–Lithuanian Commonwealth.

The origins of the szlachta are obscure and are the subject of several theories.[1]:207 Traditionally, its members were landowners, often in the form of "manorial estates" or so-called folwarks.[2] The nobility won substantial and increasing political and legal privileges for itself throughout its entire history until the decline and end of the Polish–Lithuanian Commonwealth in the late 18th century. Apart from providing officers for the army, among its chief civic obligations were electing the monarch, plus filling advisory and honorary roles at court, e.g., Stolnik - "Master of the King's Pantry," or their assistant, Podstoli, and in the state government, e.g. Podskarbi, "Minister to the Treasury". They served as elected representatives in the Sejm (National Parliament) and in local Sejmiki assemblies, appointing officials and overseeing judicial and financial governance, including tax-raising, at the provincial level. Their roles included Voivodeship, Marshal of Voivodeship, Castellan, and Starosta.[3]

The szlachta gained considerable institutional privileges between 1333 and 1370 in the Kingdom of Poland during the reign of King Casimir III the Great.[1]:211 In 1413, following a series of tentative personal unions between the Grand Duchy of Lithuania and the Crown of the Kingdom of Poland, the existing Lithuanian-Ruthenian nobility formally joined this class.[1]:211 As the Polish–Lithuanian Commonwealth (1569–1795) evolved and expanded in territory, its membership grew to include the leaders of Ducal Prussia and Livonia. During the Partitions of Poland from 1772 to 1795, minor szlachta began to lose these legal privileges and social status, while elites became part of the nobility of partitioning countries.

Although szlachta members had greatly unequal status due to wealth and political influence, few official distinctions existed between elites and common nobility. The juridic principle of szlachta equality existed because land held by szlachta was allodial,[4] not feudal, having no requirements of feudal service to a liege Lord.[5][6] As szlachta land tenure was allodial, not feudal,[7] this produced a disdain for distinction by way of titles.[8] The relatively few hereditary titles in the Kingdom of Poland were bestowed by foreign monarchs, including personal hereditary titles granted by the Pope — see Feliks Sobański. In the Grand Duchy of Lithuania, Ruthenia, and Samogitia princely titles were mostly inherited by descendants of Old Lithuanian-Ruthenian Rurikid and Gediminids princely families, or by princely dynasties of Tatar origin settled there.