She has done research in palliative care and has a federal grant for interdisciplinary palliative care education. A national leader in her advanced-practice nursing specialty, Callahan has published extensively on pain, palliative care and nurse anesthesia. When coming to Marquette, she set goals of creating a vision for the future and building research programs, community partnerships and alumni relationships. She implemented the doctor of nursing practice program. She led faculty in revising the college vision, mission and strategic plan and restructured college administration to support the plan.