The aim of this thesis is to explore the relationship between the surrounding world and the library with respect to the library’s need to provide a Library 2.0 web site. We also explore the relationship between the physical and the virtual library. Our research objects are the public libraries of Stockholm and the Umeå region, that maintain the web sites Biblioteket.se and minabibliotek.se respectively. By applying Dorte Skot-Hansen's theory of rationales we found that the Stockholm public library is acting in accordance with the experience rationale, whereas the libraries of Umeå are influenced by the instrumental rationale. Furthermore, by applying Antonio Gramsci’s theories of hegemony and struggle for power and neo-institutional theory to our data, we conclude that these libraries are strongly influenced by the surrounding society to provide Library 2.0 web sites in order to maintain their position within the library field and possibly to be considered foremost in that field. By failing to implement a Library 2.0 web our research objects would risk losing their positions within the library field, a declining influence in the cultural hegemony, fewer visitors and a reduced budget. We also found that the relationship between the physical and the virtual library has not been evaluated. Furthermore we found that the web sites do not make any impact on the physical libraries. These two findings might be due to the so far rather immature implementations. / Program: Bibliotekarie