This paper examines the phenomenon of occupational hierarchies among immigrant labor groups in the United States. Using census data for 1940-2011 we document the persistent ranking of immigrant labor groups in major metropolitan areas reflected by their position in the empirical distribution of occupations based on the corresponding Duncan Socioeconomic Index values. Having established the existence and persistence of these hierarchies across regions and time we estimate a structural model of the allocation of immigrant labor to the occupational distribution on the basis of employers' perception of their perceived productivity. The model estimates suggest that while human capital characteristics are relevant determinants of location in the occupational distribution the key factor, and the cause of persistence, is the presence of immigrant networks in regional labor markets.