Academic librarians face a higher education environment with increasing accountability and diminishing resources. The value of the library is no longer assumed on campus and administrators are asked to demonstrate the library’s contribution to student success and faculty productivity. Library administrators have responded by assigning assessment duties to librarians or creating assessment librarian positions in their libraries in order to assess library value and to create a culture of assessment. But what defines an assessment librarian? What competencies and proficiencies do they need to succeed?