During the pre-confirmation debate over Supreme Court Justice Sonia Sotomayor, critics accused her of allowing her background to influence her judicial decisions. This article assesses the validity of such a claim for all sitting justices from 1875 to 2007 in one relevant policy area, immigration. In this article, we look at all 185 immigration-related decisions by the Supreme Court from its creation through 2007. Logistic general estimating equation regression analysis of Supreme Court voting on these cases suggests that justices who were nominated by Democratic presidents, who were urbanites, and who had previous judicial experience were more likely to vote in favor of immigration. However, justices who grew up in the Southwest, had Southern European ancestors, or were ideological conservatives were more hostile to immigration. Although public opinion, the unemployment rate, and the percent foreign-born in a given year did not affect justices’ votes, non-asylum cases and appeals from the Eighth Circuit were more likely to receive favorable treatment. The mean level of racial liberalism of the Senators in office during a particular justice’s confirmation hearings likewise had a large impact on his or her subsequent rulings. These findings suggest that Supreme Court voting on immigration is substantially influenced by justices’ background and political preferences as well as by some political and legal structures. These results thus support Legal Realism and New Institutionalism instead of the Traditional Legal Model of Supreme Court behavior.