In the recent past, an increase in globalisation has made the world a small place, so that intercultural encounters have become the norm rather than exception. Multilingualism and multiculturalism are widespread phenomena that shape todays world to a great extent. Every culture and language has its own set of norms and conventions for interacting and communicating with each other, whereby politeness plays an important role. This thesis is interested in the question whether multilinguals use and perceive (im)politeness differently depending on the language they use. In order to explore this question, the first half of this thesis provides theoretical background information on multilingualism and (im)politeness, while the second half presents a qualitative empirical study I conducted for this thesis. First, I will give an overview of the broad areas of multilingualism and (im)politeness research. I will focus on the subareas that are most relevant for the scope of this thesis and will deal with selected ways of defining bi- or multilingualism by focusing on approaches by Francoise Grosjean (cf. 2013) and Aneta Pavlenko (cf. 2006). Afterwards, I will briefly discuss the global extent of multilingualism and present different types of multilinguals depending on the mode of language acquisition, give a brief overview of how the perspective on multilingualism has changed over time, and provide a first insight into research on multilinguals changing behaviour. In the following, I will elaborate on the specific ways in which the behaviour of multilinguals changes with language use and explore reasons for this phenomenon.The second half of the theory section deals with (im)politeness and face. I will present Geoffrey Leechs (cf. 1983) politeness principle and maxims for politeness and Penelope Brown and Stephen C. Levinsons (cf. 1987) approach to politeness, including the latters concept of face, ways of dealing with FTAs and influences on the choice of politeness strategies. I will also take a closer look at impoliteness and examine influences on the perception of impoliteness. Next, I will discuss ways of realising politeness strategies according to Brown and Levinson (cf. 1987) and ways of realising impoliteness according to Culpeper (cf. 2011). For the second part of this thesis I conducted a qualitative empirical study on multilinguals changing use and perception of (im)politeness. The data for this study was collected in face-to-face meetings with a total of seven participants.The study is divided into three parts. The first part consists of an interview. The participants' answers form the basis for the analysis in the two subsequent sections, namely the use of (im)politeness in the form of mock-emails, and the evaluation of impoliteness displayed in two videos available on www.youtube.com. For the mock-emails the participants were asked to write a request and a complaint in both English and German. For the analysis of the mock-emails I will apply Brown and Levinsons (cf. 1987) politeness strategies and Culpepers (cf. 2011) functions of impoliteness. For the evaluation of the videos the participants were asked to answer a questionnaire on each video.The study reveals that the participants use and perceive impoliteness rather similarly in English and German, though there are some noteworthy differences concerning their use and perception of politeness. These differences appear to be connected to cultural conventions rather than to language. The most significant differences between English and German discovered are (1) that German interaction is more direct than English interaction, (2) that social status and hierarchy are more important in a German-speaking context, which leads to a greater social distance between the interlocutors and (3) that conventionalised politeness is used more frequently in English, whereas there is more genuine politeness in German.