Studies of expatriate effectiveness have tended to restrict themselves to Westerners sojourning in non-Western countries or to non-Westerners studying in the West, thereby overlooking non-Western expatriates working in Third World countries. Reconstituting diverse principles from social comparison and identity theories, attribution research, the similarity-attraction literature, psychotherapy, psychody namics, and experimental social psychology, we predict that the relationship between (a) perceived ethnic similarity to host and (b) acceptance by that host may often differ considerably in Western versus non-Western contexts. While acceptance by Western hosts may be affected by "similarity attraction reactions in some developing nations may be influenced instead by "inverse resonance", wherein collectivist hosts are comparatively unreceptive to expatriates who are ethnically similar rather than dissimilar. We discuss the potential relevance of such inverse resonance to the predeparture training of expatriates and to their inter- cultural effectiveness in the field.