The socio-psychological variables that affect bilinguals' choices of code-switching (CS) and code-mixing (CM) as a verbal strategy make prediction of their occurrence almost impossible. This research investigates the social motivations and socio-pragmatic aspects of Chinese-English CS/CM among Chinese undergraduate students. Using a questionnaire survey and interviews, the paper investigates attitude-behavior relations by considering patterns of language use and CS/CM patterns between Chinese and English in this group. The results demonstrate that the participants' highly positive attitudes toward English and the CS/CM process play a major role in CS/CM use in their daily interactions. Chinese-English bilingual students draw on their proficiency and knowledge of the two language systems to precisely and effectively convey their thoughts, intentions, experiences, solidarity, emphasis, and other aspects that affect interaction outcomes.