Reviews competing academic theories on why immigrant groups have differing naturalization rates, and reports results of comparative study indicating that institutional support for naturalization by the receiving society can make a significant difference. Aided by active Canadian government support for community groups promoting citizenship, Portuguese immigrants in Toronto achieved naturalization rates twice as high as Portuguese immigrants with similar socio-economic characteristics in Boston, where no government policies or programs promoted citizenship. It takes immigrants in the United States 30 years to reach Canadian naturalization rates of 73 percent.