Depth or Breadth? Domain-Specific Expertise and Cross-Domain Engagement in the Development of Scholarly Excellence

Scholarly excellence is often equated with deep specialization within a single domain, a premise embedded in doctoral training, peer review, and academic-evaluation systems. However, research from the emerging "science of science," drawing on large-scale analyses of publications, citations, and career trajectories, suggests a more complex relationship between expertise, cross-domain engagement, and scholarly impact. This conceptual article synthesizes insights from the science of science, cognitive research on expertise, and organizational studies to examine the roles of domain-specific depth and different forms of cross-domain engagement in the development of scholarly excellence. We argue that depth and breadth are complementary capacities whose contributions vary across career stages and institutional contexts. We distinguish between multidisciplinary exposure, interdisciplinary integration, and, in rarer cases, transdisciplinary contributions that extend beyond existing boundaries. Domain-specific expertise supports technical mastery, credibility, and efficient knowledge accumulation, whereas integrative forms of cross-domain engagement facilitate recombination, problem reframing, and long-term intellectual influence. We further show how academic-reward structures favor depth while discounting integrative contributions. We conclude by outlining implications for doctoral education, faculty evaluation, and research policy, and by proposing a developmental framework that supports diverse trajectories of scholarly excellence.