The internationalization of higher education has led to an increased demand for English-medium instruction (EMI) in globally diverse classrooms. Faculty at higher education institutions (HEIs) in both English-dominant and English-non-dominant contexts often struggle with this requirement due to insufficient institutional support. While applied linguists have extensively researched language proficiency for teaching and learning, the development of faculty competencies in multilingual, multicultural classrooms extends beyond language alone. Faculty developers at HEIs, who may specialize in areas such as curriculum design, intercultural communication, and teaching through English, often lack comprehensive training to support faculty in creating internationalized curricula for diverse student cohorts. To address this challenge, the transnational European project, Educational Quality at Universities for inclusive international Programmes (EQUiiP), was established. EQUiiP provides modular training for faculty developers, focusing on five key areas: the international classroom, internationalizing course design, intercultural group dynamics, the role of language, and feedback and reflective processes. The program includes an intensive four-day seminar followed by practical application and reflection, enabling faculty developers to effectively train EMI instructional faculty. This chapter explores the implementation of EQUiiP, offering empirical examples and discussing the pros and cons of various faculty development approaches. It emphasizes the importance of assessing professional development outcomes and provides a concrete example of such assessment.