Based on a tentative model and a sample of 215 university international students of the second year studying Chinese in the PRC, this research studied the relationships among Motivation in Second Language Acquisition (SLA), Socio-cultural Adaptation, Academic Adaptation, Language Achievement and Institutional Persistence, and evaluated their contributions in a causal model of Adaptation and SLA. The results of the study indicated that the theoretical model provided good fit to the data, and generally supported Gardner's (2005) socio-educational model except that Language Anxiety was not found to have a cause and effect relationship with Language Achievement. Instrumentality seemed to significantly predict the variation of Persistence together with Academic Adaptation. Moreover, Saving Other's Face Scale seemed to be important to predict Motivation, Socio-cultural Adaptation and especially Academic Adaptation. Copyright © 2006 Office of Research, Faculty of Education, University of Hong Kong.