“…While our research is similar in some respects to earlier work (Southern California Association of Governments, 1984;Muller and Espenshade, 1985;Manson et al, 1985;McCarthy and Valdez, 1986;Bean et al, 1988;Espenshade and Goodis, 1988;Heer, 1990a + b, andHeer et al, 1992), it is unique in being the first in the 1990s to estimate the UM population from survey data; separating UMs from legal Mexican immigrants at the individual level; and inquiring directly into the validity of contemporary restrictionist immigration sentiment based upon labour market competition with UMs. Moreover, although others have made estimates of this population (Bean et al, 1984;Bean et al, 1988;Hill and Pearce, 1990;Woodrow-Lafield, 1993;and Warren, 1994), they have done so in a relatively general manner. No prior research, except for Heer et al (1992) has examined the over-or underrepresentation of UMs in specific occupational, industrial and class of worker categories in comparison with other ERGs which comprise the total labour force.…”