The Workers' Party was launched by a heterogeneous group made up of militants opposed to Brazil's military government, trade unionists, left-wing intellectuals and artists and Catholics linked to the liberation theology on 10 February 1980 at Colégio Sion in São Paulo, a private Catholic school for girls. The party emerged as a result of the approach between the labor movements in the ABC Region such as the Conferência das Classes Trabalhadoras (Conclat), later developed into the Central Única dos Trabalhadores (CUT) which carried major strikes from 1978 to 1980; and the old Brazilian left-wing, whose proponents, many of whom were journalists, intellectuals, artists and union organizers, were returning from exile with the 1979 Amnesty law, many of them having endured imprisonment and torture at the hands of the military regime in addition to years of exile. Dilma Rousseff herself was imprisoned and tortured by the dictatorship.