The book discusses and compares different ways of using Web 2.0 tools in services of Polish book institutions. This study uses the mixed methods research to explore the extent and forms of social media usage in the services of book institutions in Poland, with an emphasis on showing the differences in the way they are used by commercial and non-commercial institutions. A survey of selected public libraries, bookstores and publishers of general or literary profile was conducted, supported by an interview with representatives of the surveyed institutions. Quantitative analysis was used to examine the extent and forms of social media usage in the activities of the book institutions, whereas qualitative analysis helped to explain the reasons for the observed phenomena and to indicate subject fields for further consideration. The overall results suggest that: book institutions use Web 2.0 mostly to inform about their offer and to support promotion; social networking sites, one of the analyzed forms of Web 2.0, are now next to web pages and e-mail the most commonly used tool for information and communication; book institutions use Web 2.0 to conduct services, and - in the case of commercial institutions - book trade, although significantly less than in the case of information and promotion; respondents' attitude to social media is not yet clearly defined, but the relatively large group of them considered social media as an important tool, pointing primarily their use in promotion. The results of the study, at the theoretical level, deepened and clarified social media issues, particularly in the area of research related to the use of Web 2.0 tools in services. The results of the study can be practically used to develop standards for the online services provision and to improve the flow of information about book institutions offers through social media.