This study addresses some of these gaps by examining the applicability of the E-S-QUAL instrument, which was developed by Parasuraman et al. (2005), for measuring the service quality of library social media services. E-S-QUAL has never been applied in the library service field. Nine hypotheses address the applicability in terms of 1) the scale’s reliability and validity, 2) the relationships between userperceived service quality and three related variables to service quality (overall quality, customers’ perceived value of information, and loyalty intentions), and 3) the scale’s potential to identify differences between user-perceived importance for a library social media service and theirperceived performance of the service