Academic librarians have been engaged in embedded librarianship for nearly 15 years, yet there are few published research studies on the impact of physically embedded librarians, who work alongside departmental faculty. This study leveraged a change in reference service to analyze what happened when subject librarians moved from the library services desk to spending a significant part of their workday in the academic departments they serve. Reference and instructional transactions increased significantly, and novel instances of collaboration and integrations arose. Based on the results, this study proposed a developmental model for physically embedded librarianship.