Musicians face particular communication and identity challenges when working with music and people from other cultural groups. Those challenges impede efforts to promote intergroup projects and rapport. Intercultural communication studies have made significant contributions in understanding how people work and live across cultures but do not explicate the unique ways in which professional musicians engage internationally. Thus, there is a need to research musicians’ intercultural practice and identity development. This qualitative study addresses the gap through three research questions: 1) What aspects of intercultural communication and identity processes are significant to musicians when they begin intercultural music practice? 2) What challenges do musicians report during intercultural music projects? 3) What keeps musicians engaged in intercultural music practice in the long term? Semi-structured interviews were conducted with 17 music professionals engaged in intercultural music-making with questions about their projects and experiences. These were complemented with field notes from observations of six respondents’ live concerts. Recordings and written accounts relating to participants were also collected from the internet to inform the analysis. Purposive sampling and theory-led thematic analysis were guided by a priori themes developed from Young Yun Kim’s and Etienne Wenger’s theoretical framework. Kim’s Integrative Theory of Communication and Cross-cultural Adaptation and Wenger’s Communities of Practice theory place individuals’ music careers into intercultural and social learning contexts. The theoretical notion of boundaries - boundary crossing and boundary learning - has also been used to address socio-cultural differences that result in discontinuities in activities and interactions. Codes were arranged under a three-part dynamic of encounter, stress, and learning, which describes how individuals cross groups and work on differences perceived. The findings delineate how musicians experience and learn at musical and cultural boundaries mixedly. Music enabled them to coordinate temporarily by providing nonverbal routines, working arrangements, enjoyments, and promising identities essential in motivating individuals to start intercultural music practice. However, language proficiency, social communication, and cultural adaptations become more critical as musicians work long-term across cultures, organise complicated projects, and negotiate nuanced meanings. Although respondents may state cosmopolitan ideals and intercultural objectives, their focus often gravitated back towards musical issues that emerged in their performance and organising work. Finally, respondents’ experiences suggest that organisers with intergroup mediation objectives should consider arranging language training and designing for meaningful intercultural experiences. It is beneficial for musicians to know what cross-cultural communication and adaptation would be expected and how to seek cultural informants’ help. The findings contribute to theory by offering a novel manifestation of professional musicians’ intercultural activities as boundary phenomena. The diverse cultural experiences told from the musicians’ perspectives enriches our social and psychological understanding of intercultural challenges. These musicians’ projects and words demonstrate how crossing boundaries, with mutual interest and creative adaptation in musical activities, opens up possibilities for new intercultural collaborations, rapport, ideas, and identities.