Leading Layman

Unlike Mr. Walesa, the man chosen to lead Poland's first postwar Cabinet not dominated by Communists did not come up from the successive rounds of labor struggle. He had long ago emerged as a Roman Catholic lay leader, playing a major role in guiding the Pax group of young Catholics who in 1956 backed the liberalizing policies of Wladyslaw Gomulka, the Communist Party chief, hoping in exchange to obtain a gradual expansion of political rights.

In exchange, Mr. Gomulka in 1957 allowed the establishment of the Catholic Intellectuals Clubs, in which Mr. Mazowiecki still plays a leading role, and in 1958 permitted the founding of the critical Catholic monthly Wiez, or Link, whose first editor Mr. Mazowiecki became. Wiez was liberal and grew increasingly antagonistic to the Communist regime. In the 1970's, Mr. Mazowiecki gave his support to the Workers' Defense Committee, which protected workers attacked by the Communist Party for their labor activism, and helped establish the underground universities that kept alive the flame of independent culture and scholarship.

In 1980, he emerged as the moving force behind an effort to link Polish intellectuals with the militant workers in the northern shipyards of Gdansk, who were engaged in a crucial battle with the Communist authorities not only for more pay but also for broader labor rights.

In August 1980, the crucial month of labor strife that led to the birth of Solidarity, Mr. Mazowiecki initiated an appeal signed by 64 intellectuals -scholars, scientists and cultural figures from around the country - in support of the workers' demands.

''In this struggle the place of the entire progressive intelligentsia is at their side,'' the signers said of the striking shipyard workers in the text Mr. Mazowiecki helped frame. ''That is the Polish tradition, and that is the imperative of the hour.''