Interdisciplinarity is a powerful driver of knowledge creation, research and innovation. Although it has always been part of the scientific enterprise, interdisciplinarity has rapidly developed in many scientific areas and has become an important issue for universities riding on the wave of dramatic societal changes and challenges, and an increasingly collaborative research system. LERU regards disciplinarity and interdisciplinarity as equally important to find solutions to pressing problems. Interdisciplinarity is essential to the evolution and reconfiguration of disciplines and the emergence of new ones. But without thorough disciplinary knowledge it would not be possible to conduct interdisciplinary research to begin with. Making interdisciplinarity count in universities requires significant levels of investment and commitment within a system built primarily for disciplinarity. Universities that succeed in creating a virtuous circle between disciplinarity and interdisciplinarity, in education, research and innovation, are well positioned to reap major benefits. The paper formulates recommendations for universities, governments and funders on how they can incorporate interdisciplinarity in their policies and programmes.