She teaches graduate courses in the school library media certification program. Johnston worked as a school librarian for 13 years in Georgia before obtaining her PhD at Florida State University. Johnston’s research and publications focus on the school librarian as a leader, the school librarian's role in technology integration, and school librarianship on a global level. Johnston is the author of numerous articles in journals such as School Library Research, School Libraries Worldwide, School Library Connection, and Tech Trends. She is currently the co-editor for School Library Research and PI on for the REALISD Project, an IMLS funded grant, to provide professional development for school librarians to support STEM education efforts in their schools.