The Polish-Lithuanian Parliament of 1569– 1795 consisted of three houses: The King, Senate and House of Representatives. The King and Representatives were elected in general election. The members of the Senate were arbitrarily appointed by the King for a lifetime tenure. There is an extensive literature on the forming of the Polish-Lithuanian elite of power in the 16th–18th centuries. The article proves that the literature missed several vital aspects of the issue. Even if the appointments to the Senate were arbitrary, they reflected the real position of politicians in the country’s social network, as if the social network were the real ruling power in the country, influencing the King’s decisions. And the status of politicians was better connected to the network position of their mothers and wives than to their surname and male line.