This article discusses the organizational and administrative structure of the Polish–Lithuanian Commonwealth.
The Polish–Lithuanian Commonwealth was a confederative republic of the period 1569–1795, comprising the Kingdom of Poland, the Grand Duchy of Lithuania and their fiefs. The Commonwealth was governed by the Parliament (Sejm) consisting of the King, the King-appointed Senate (Voivodes, Castellans, Ministers, Bishops) and the rest of hereditary nobility either in person or through the Lower Sejm (consisting of deputies representing their lands). The nobility's constitutional domination of the state made the King very weak and the commoners (burgesses and peasants) almost entirely unrepresented in the Commonwealth's political system.
The Commonwealth's administrative system was a pre-bureaucracy. In terms of Max Weber's tripartite classification of authority, it was, as with other contemporary monarchies, largely based on "traditional domination". There was, however, evidence of "rational-legal authority" in the nobility's respect for laws such as the Pacta conventa.
The Privy council and Upper chamber of the First Republic's Sejm (parliament, or diet) was the Senat (now Senate), comprising Bishops, Voivode, Castellan and ministers (central officials). The list of dignitaries eligible to serve in the Senat had been finalized when, in the Union of Lublin (1569), the Kingdom of Poland and the Grand Duchy of Lithuania were transformed into the confederal state of Crown of Poland and Grand Duchy of Lithuania, the Polish–Lithuanian Commonwealth.