In urban economics, and more recently in the international economics litera
ture, agglomeration has been offered as a principal determinant of new inve
stment. Yet agglomeration has rarely been subject to precise statistical te
sts. In this paper, the availability of detailed urban and regional data fo
r Portugal allowed for a close study of the spatial choices for newly creat
ed foreign-owned plants. It appears that agglomeration economies are decisi
ve location factors. Service agglomeration has a notably strong effect, whi
le industry-level localization economies and urbanization externalities are
verifiable location determinants as well. Distance from the principal citi
es is statistically significant, but there is no evidence that local labor
costs matter. (C) 2000 Academic Press.