This chapter discusses the use of social networks in Web services with focus on the discovery stage that characterizes the life cycle of these Web services. Other stages in this life cycle include description, publication, invocation, and composition. Web services are software applications that end users or other peers can invoke and compose to satisfy different needs such as hotel booking and car rental. Discovering the relevant Web services is, and continues to be, a major challenge due to the dynamic nature of these Web services. Indeed, Web services appear/disappear or suspend/resume operations without prior notice. Traditional discovery techniques are based on registries such as Universal Description, Discovery and Integration (UDDI) and Electronic Business using eXtensible Markup Language (ebXML). Unfortunately, despite the different improvements that these techniques have been subject to, they still suffer from various limitations that could slow down the acceptance trend of Web services by the IT community. Social networks seem to offer solutions to some of these limitations but raise, at the same time, some issues that are discussed in this chapter. The contributions of this chapter are three: social network definition in the particular context of Web services; mechanisms that support Web services build, use, and maintain their respective social networks; and social networks adoption to discover Web services.