Background Although interdisciplinarity has been a subject of interest and debate for decades, few investigations of interdisciplinary education exist. Existing studies examine the effects of interdisciplinary experiences on students' development of generic cognitive skills but not the development of interdisciplinary competencies. Purpose/Hypothesis This study sought to explore how engineering students' characteristics, college experiences, and engineering faculty beliefs relate to students' reports of interdisciplinary competence. Design/Method The study used a nationally representative survey sample of 5,018 undergraduate students and 1,119 faculty members in 120 U.S. engineering programs at 31 institutions. Using hierarchical linear modeling, we investigated the relationships among students' curricular and co‐curricular experiences and faculty beliefs regarding interdisciplinarity in engineering education on students' reports of interdisciplinary competence. Results This study found that a curricular emphasis on interdisciplinary topics and skills, as well as co‐curricular activities, specifically, participating in nonengineering clubs and organizations, study abroad, and humanitarian engineering projects, significantly and positively relate to engineering students' reports of interdisciplinary skills. Faculty members' beliefs regarding interdisciplinarity in engineering education moderated the relationships between particular co‐curricular experiences and students' interdisciplinary skills, as well as between curricular emphasis and students' interdisciplinary skills. Conclusions This study identified a small set of experiences that are related to students' reported development of interdisciplinary competence. The study points to the critical role of the curriculum in promoting interdisciplinary thinking and habits of mind, as well as the potential of co‐curricular opportunities that bring engineering students together with nonmajors to build interdisciplinary competence.