It is clear from the literature that clients the world over expect much the same services of their advertising agency, regardless of industry type or company size— thus it is very difficult for agencies to segment their markets in a meaningful way. This research describes a field test of the idea that clients' market orientation provides such a segmentation base. When selecting an advertising agency, market-driven companies exhibit quite different organizational behavior and hold different evaluative criteria than do less market-driven companies.This work was completed with help from a research grant from Hallym University.