Although few controversies in our political environment are as contentious as the current debate over immigration policy, the research on public opinion toward immigration is quite limited. In particular, we know relatively little about the contextual determinants of opinions on immigration issues. We address this issue by investigating the impact of migrant context on Anglo opinions toward immigration. We find that Anglo support for increased immigration is directly related to the size of the documented migrant population. Conversely, as the relative size of the undocumented migrant population increases, Anglo support for increased immigration decreases. We conclude with a discussion of the relevance of our findings for the study of immigration opinion, in particular, and the study of intergroup relations more generally.