Abstract. Finding books in large libraries can be difficult for novice library users. This paper presents the current status of SmartLibrary, a web-based guidance application helping library customers in this task. We present a comparative evaluation where users tested the service in the main library of University of Oulu with fixed and mobile devices. The evaluation confirmed that SmartLibrary is a useful service for novice library customers; more experienced patrons prefer the traditional shelf classification. The users considered the service easiest to use with a public desktop terminals. However, the possibility of using the guidance in a PDA or a mobile phone in larger libraries was appreciated.