Cantonese is the mother tongue of the majority of Chinese people in Macao and widely used in the Macao community. Other languages such as English, Portuguese, Mandarin and other Chinese dialects are used as well in daily communication. Code-switching is becoming more common in the speech of bilinguals in Macao. It is one of the major issues in bilingualism and there has been much more research on the topic in the last several decades. This dissertation reports the findings of a survey on teachers’ and students’ attitudes towards code-switching in the university classroom. The participants are a group of 9 Macao-born and 9 Mainland-born Chinese students studying at the University of Macau and two teachers working in the Department of Government and Public Administration. 18 students filled out a 17-item questionnaire which aimed to assess their language use and attitudes towards code-switching, while three Macao students and three Mainland Chinese students and one teacher took part in an interview. The findings suggest that more local Macao students, compared to the Mainland Chinese students, feel that classes could be understood more easily by the alternating use of Cantonese, Mandarin and English. In addition to the questionnaire and interview, 12 hours of lectures were audio-recorded and analyzed. The analysis reveals that teachers make use of specific code-switching patterns (i.e. from Cantonese to Mandarin or from Mandarin to Cantonese) to achieve communicative and pedagogic functions gearing towards the students’ education background and the multilingual settings in Macao. The other objective of this dissertation is to apply the Markedness Model (Myers-Scotton 1993, 2006), Conversation Analysis (Auer. 1984, 1995, 1998) and other theoretical frameworks to analyze code-switching data collected from Cantonese-English bilingual teachers in the university. The analysis focuses on how teachers use code-switching to fulfill a variety of communicative functions and how they build up a solidarity relationship with students by certain patterns of code-switching in class.