This article gives an overview of the relationship between Swedish Social Democratic women and the Natonal Association for Women's Suffrage (L.K.P.R.), based on a study of how the issue of co-operation was debated at women's congresses between 1907 and the constitutional reform of 1919/1921. L.K.P.R., founded in 1903, had adopted a platform that demanded women's right to vote on the same conditions as men, meaning that women with low incomes would not be enfranchised because of the existing income requirements. This made co-operation controversial. Positions adopted by the International Congress of Socialist Women and the International Suffrage Alliance Conferences stirred further conflicts. However, co-operation took place in practice over a nationwide petition for women's political rights in 1913–14. Furthermore, many Social Democratic women were individual members of local chapters of L.K.P.R. It is therefore important to use biographical studies to nuance the picture of two separate movements.