Using 1990 census data, the authors compare 77 immigrant and ethnic gr
oups in the 16 largest metropolitan regions in the United States. They
find that the interaction effect of location and ethnicity on ethnic
entrepreneurship is evident not only in self-employment rates but also
in niche concentrations and niche competition. Their results reveal a
distinction between mainstream groups and nonmainstream groups. Compa
red to mainstream groups, nonmainstream groups are more context resist
ant. That is, they concentrate in few entrepreneurial niches and displ
ay high niche continuity across metropolitan regions. Group competitio
n influences niche concentrations, but an adverse impact on black entr
epreneurship is not apparent.