Understanding information organization is a key component to navigating digital library environments as an information professional. While traditionally thought of within the areas of assessment and evaluation, citation indexing is another form of organization and navigation, and learning about it can transform one's knowledge of the information environment. In this article, McLaughlin and Tucker argue that an understanding of citation indexing should be emphasized to all library and information science (LIS) students as a way to further develop search expertise, and to enhance reference services and digital information literacy in any information setting. Situating this learning experience within the theory of threshold concepts, they provide evidence from student discussions of the transformative nature of a practical and conceptual understanding of citation indexing.