This article explores continuities and discontinuities in Polish Catholic discourses on family planning across a time span that tends to be divided in the historiography on Poland and political history in general. The period we analyse begins in 1930, with the pivotal encyclical Casti connubii defining church doctrine on contraception, and ends with the legalization of abortion in 1956, and a state-sponsored family planning campaign the following year. In order to reconstruct Catholic teachings on marriage and family planning we examine advice publications that received official church approval, paying particular attention to their gendered dimensions, the emphasis placed on marriage, and the ‘calendar’ method. Although our research includes three politically and socially distinct periods, we argue that the content of Catholic teachings on family planning in Poland was consistent throughout. We also show that, although there were some distinct national characteristics, the Polish Catholic discourse on family planning resembled to a great extent the developments in other countries, particularly in regard to visions of marriage and sexuality. As we delineate, by engaging in the discussion on family planning, Catholic authors acted as active constructors of modernity, construed in both periods in relation to science and nationalism.