This paper analyzes the role of source country culture on gender roles for labor market assimilation of immigrant women in Sweden. Sweden ranks as one of the world's most gender-equal countries and at the same time a recipient of many immigrants from countries with more traditional views on gender roles and gender equality. I find that the labor force participation of immigrant women in Sweden is related to their source country culture, in the sense that women from countries where women's labor market participation is low (high) also have low (high) participation in the Swedish labor market. However, all immigrant women assimilate towards, but do not reach parity with, the participation rate of native women, and the difference between women from high- and low-participation countries diminishes with length of residence in Sweden. This indicates that source country culture on gender roles does not have a persistent effect on immigrant women's labor market participation in Sweden. Furthermore, the results highlight the importance of taking into account unobservable time-constant individual and source country factors when estimating the relationship between source country culture and immigrants' labor market outcomes. Neglecting to control for these factors could lead researchers to misrepresent the rate of assimilation and overstate the effect of source country culture.