Professional engineering work occurs in dynamic, complex contexts that require engineers to leverage various skills beyond their technical competencies to work productively with different stakeholders. Problem-solving is not merely a technical endeavor; educators and practitioners have long realized the synergistic connection between technical proficiency and complex personal and interpersonal competencies, such as critical thinking and communication skills. Since the 1990s, the topic of transversal or professional skills has been a common thread in engineering education literature. Engineering accreditation bodies such as Accreditation Board for Engineering Technology (ABET) and Commission des titres d’ingénieur (CTI), and engineering curriculum models such as the conceive-design-implement-operate (CDIO) have highlighted the importance of various transversal skills in professional engineering work. Today, there is a general agreement among engineering educators and scholars about the value and benefits of transversal skills. What is less clear is which specific skills should be considered transversal and how those skills can be categorized and defined. Efforts in settling these issues ultimately help engineering programs to have a clearer picture of which skills are (and are not) well integrated and assessed in their curricula. This concept paper discusses a framework for categorizing transversal skills. We build on the relevant literature and the ongoing educational practices in prioritizing transversal skills at the École polytechnique fédérale de Lausanne (EPFL) to bring visibility to essential graduate skills and attributes, including those that are often underemphasized.