The purpose of this thesis is to investigate the function of the museum library. The methodused consisted partly of literary studies, and partly of field investigations, conducted mainlyin the form of interviews.Two different sets of field studies have been conducted. The first one is an investigation ofthe museum libraries in Goteborg. After a preliminary study, three of these have been selectedfor further investigation. These are the libraries of Göteborgs Konstmuseum, GöteborgsStadsmuseum and Röhsska museet. Five employees from each museum have been interviewed,and asked to give their opinions of the library and its function, and also to describehow they used it. To broaden the perspective of the essay, an additional field study wasmade. In this, the libraries of Byggnadsvård Nääs, Stockholms Stadsmuseum and SkaraLänsmuseum were investigated. All these libraries exhibit a slightly different function thanthe others, mostly in giving greater attention to the public part of their work. The thesis concludesthat museum libraries can have served different functions, but the fundamental onemust always be to provide information services for the museum itself. The library is a tool forthe museum personnel, and their access to the information must be the topmost priority ofevery museum library. Once this is seen to, however, the library can have several other functions.Museum libraries are a source of information for researchers. It can become a way forthe museum to open up its collections to the museum visitor. Pictures and archival materialcan be computerized and made accessible through the museum library. The library can alsobe a way for the museum to market itself, by attracting visitors to the museum. In addition tothis, the library can be an arena for other activities to take place in, a gateway between themuseum and the visitor.