To illuminate barriers to collaboration, this study examines who participates in cross-boundary scholarly collaboration most often and which types of boundary crossing (disciplinary, institutional, role) are engaged in most often. The data of this study came from an interdisciplinary consortium with five partner institutions, including one Historically Black College and University (HBCU). The core disciplines involved in the consortium are life sciences, computer science and math and engineering. Through statistical analysis, we determined that members of the consortium engaged more in interdisciplinary research than inter-institutional research. Participation in all boundary crossing collaborations was greater at the HBCU and students and postdocs were less likely than academics to cross-institutional boundaries.