School librarians are specialized educators who lead technology initiatives and who adjust their programs annually to local and national trends. The profession's changing nature requires perpetual learning unmatched in other educator positions. In this survey study, school librarians reported their perceptions of professional learning in Twitter, Facebook, Instagram, Pinterest, and LinkedIn using a quantitative questionnaire. In addition, participants described their perceptions through comments. The study sought answers to three research questions: (1) how do school librarians perceive user roles, activities, motives and barriers in different platforms used for professional learning, (2) how do results compare among platforms, and (3) how do results divided into user roles align across platforms. This multi-factor research captured four-facets of professional learning in one study, creating platform and user role profiles. Most participants used multiple platforms for learning, but they used platforms differently. Twitter and Facebook were the most popular platforms, followed by Instagram. Most participants reported few habitual activities, but diverse motives. Barriers were limited. The Twitter, Facebook, and Instagram profiles indicated rich learning opportunities, whereas the Pinterest and LinkedIn profiles indicated narrow use. Participants selected user roles based on their learning goals: Community Leader, Contributor, Networker, Active Lurker, and Passerby. Most participants identified as Active Lurkers. The user role profiles were more comprehensive than the traditional lurker-poster dichotomy. The school librarian results affirmed many findings in educator populations, but also suggested differences may exist between the populations. This exploratory study opens new avenues for population-specific research in how school librarians approach professional learning in a dynamic field. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]