Using data for the period 1968–2001, this article assesses the influence of partner choice and origin country characteristics on the propensity of immigrants to naturalize in Sweden. Marriage to a foreign‐born Swedish citizen increases the naturalization propensity, and its effect increases strongly when the spouse naturalizes during the same year. The analysis suggests that a lower level of civic and political freedom or relative GDP per capita in the individual's country of origin is associated with an elevated probability of naturalization. During the period of study, originating from a country which allows for dual citizenship did not systematically elevate the probability to naturalize; this probability was accentuated, however, if the individual originated from a context characterized by a low degree of civic and political freedom.