This study examines the quality of services at Iran’s Central Library of Management and Planning Organization (MPO) from the viewpoint of itsusers. The research was conducted in two phases: First, the library and its services were compared to the Standards for Special Libraries published bythe National Library of Iran (NLI). The library was found to meet most of the standards. Second, the quality of service provided by the library atexpected and observed levels was examined from the viewpoint of organizational and non-organizational members using a modified version ofthe SERVQUAL questionnaire. Findings showed a significant was difference between two (expected and observed) levels, meaning that users’expectations have not been met. The most significant difference related to “appropriate collection of information resources”. The results also showedthere was no significant difference between organizational and non-organizational users’ opinions about the quality of services. Findingsalso showed that “relevant information services” was the priority of user groups-users emphasized the need for timely and accurate information.There was a correlation between the rate at which the library conformed to the national standards and users’ expectations of quality.