  Interdisciplinary research has emerged as a hotbed for innovation and a key
approach to addressing complex societal challenges. The increasing dominance of
grant-supported research in shaping scientific advances, coupled with growing
interest in funding interdisciplinary work, raises fundamental questions about
the effectiveness of interdisciplinary grants in fostering high-impact
interdisciplinary research outcomes. Here, we quantify the interdisciplinarity
of both research grants and publications, capturing 350,000 grants from 164
funding agencies across 26 countries and 1.3 million papers that acknowledged
their support from 1985 to 2009. Our analysis uncovers two seemingly
contradictory patterns: Interdisciplinary grants tend to produce
interdisciplinary papers, which are generally associated with high impact.
However, compared to disciplinary grants, interdisciplinary grants on average
yield fewer papers and interdisciplinary papers they support tend to have
substantially reduced impact. We demonstrate that the key to explaining this
paradox lies in the power of disciplinary grants in propelling high-impact
interdisciplinary research. Specifically, our results show that highly
interdisciplinary papers supported by deeply disciplinary grants garner
disproportionately more citations, both within their core disciplines and from
broader fields. Moreover, disciplinary grants, particularly when combined with
other similar grants, are more effective in producing high-impact
interdisciplinary research. Amidst the rapid rise of support for
interdisciplinary work across the sciences, these results highlight the
hitherto unknown role of disciplinary grants in driving crucial
interdisciplinary advances, suggesting that interdisciplinary research requires
deep disciplinary expertise and investments.
