This article proposes that understanding information literacy as a social practice is a threshold concept for academic information literacy librarians. While the social nature of information literacy has been theorized for more than 25 years, the noted theory-to-practice gap in this area suggests a new question to be raised. This study explores how practicing academic librarians come to adopt this understanding, if at all. The article reports on the development of a grounded theory to explain the theory-to-practice gap. Participants were 17 academic instruction librarians who participated in interviews. A grounded theory approach was used to analyze the data and found that a threshold concept might explain a shift from seeing information literacy as skills-based to practice-based. Implications for LIS education include explicit discussion of this threshold concept as well as including the related concept of information landscapes in the LIS curriculum.