Advancing globalisation processes entail that businesses increasingly have to orient themselves internationally in order to remain competitive. Growing labour mobility and international economic networks imply a rise in intercultural contacts, and thus a rising demand for intercultural competence. However, the relevance of intercultural competence is often underestimated outside of the academic community. In order to elucidate the significance, the necessity and areas of application of intercultural competence, an explorative (primarily qualitative) study was conducted with students and professionals with and without a migration background. The central objects of study were the experience-based attitudes of students and professionals. In this qualitative study, 61 structured interviews were examined using a content analysis. After the presentation of a definition of the construct, the interviewees were asked about aspects of intercultural competence. The aspects mentioned most frequently was a general open attitude, followed by impartiality, self-reflection of one’s own culture and person, and lastly, culture-specific knowledge. Regarding the areas in which intercultural competence is needed, respondents mentioned the education sector most frequently, followed by references to business, as well as internationally operating companies. These results provided indications for the development of a measurement instrument of intercultural competence and related constructs. Therefore, another qualitative study was conducted with 249 interviewees to identify aspects of both, general intercultural competence, and culture-specific competence in a German cultural environment. Eleven dimensions of general intercultural competence, relating to personality traits, relational attitudes, and skills, were identified in a content analysis of the interviews. Further, six culture-specific aspects were derived from the interviews, containing culture-specific knowledge, norms, and communication skills. Based on the responses, three scales were generated: two graded response scales for general intercultural competence and culture-specific competence, and a culture-specific situational judgement test. The resulting measuring instruments were thereafter validated in a quantitative study with a total of 6338 participants, including students, professionals, and unemployed, each with German background, international background, refugee background, or emigrated. The scales’ and subscales’ reliability and validity were tested in the individual subsamples, using methods from both classical test theory and item response theory. The items were reviewed twice, based on the calculated item characteristics, as well as on results from a focus group with immigrants and expert discussions. The present paper thus contributes to a differentiated understanding of cross-cultural and culture-specific aspects of intercultural competence in an increasingly culturally diverse global society.