Recent waves of migration to Europe and North America have fueled intense debates and public anxieties over the potentially adverse economic, social and cultural impacts of immigration. In this context, migrants' socioeconomic status plays a critical role in shaping reactions to new arrivals, with poorly-educated, low-skilled immigrants consistently eliciting greater opposition on measures of explicit attitudes. Little is known however about the effect of immigrants' socioeconomic status on exclusionary reactions rooted in implicit outgroup biases. We report findings from a field experiment examining implicit bias against high- and low-status immigrants in Milan, Italy. We measure natives' implicit biases as manifested in aversive reactions to sharing a personal space with immigrants in everyday encounters. Results from 831 trials demonstrate that immigrants are physically avoided regardless of their socioeconomic status. Further exploratory analysis reveals this effect to be driven by native women avoiding contact with immigrant men. We interpret these results within a dual process framework which separates implicit negative reactions towards immigrants from explicit attitudes based upon instrumental comparisons of the potential impact of high- vs. low-skilled immigration.