Most scholarly works on the effects of growing cross-Strait economic relations stay at the macro-level, and few have touched upon interpersonal contacts and attitude changes at the micro-level. Yet it would be difficult to predict or make sense of incremental changes at the macro-level without referring to developments at the micro-level. The aim of this paper is to examine whether the Taiwanese living in the mainland have been assimilated into the local society after years of interactions with local people. If so, what factors have caused these changes, and what implications do they have for future cross-Strait relations? This article reports and discusses the results of a survey project about the social and political attitude of Taiwanese living in the mainland. In this survey project, we interviewed more than 200 Taiwanese living in the Greater Shanghai region and Dongguan region in the summer of 2009. In this most extensive survey so far in the mainland, we find that ”class” and ”identity” are the two most important factors affecting the Taiwanese's assimilation into the local society, with the former explaining how they mingle with the local people and the latter shaping the degree of their relationships and psychological acceptance of the local society.