This paper examines the idea, commonly expressed in the Library and Information Services (LIS) literature, that public libraries have a growing role as developers of social capital, and brings to bear some of the growing body of research into public libraries and social capital. It reviews definitions of social capital by writers outside the LIS sector and outlines the main strategies taken by public librarians who attempt to contribute to social capital, such as community outreach, provision of meeting places and provision of universal services to the public. It discusses the public library as a community centre of learning, with particular reference to the fields of ICT access and training and of information literacy, and the public library as a proactive developer of social networks and partnerships. It concludes by examining research studies that throw light on the complex question of whether public libraries can and do generate social capital and on the kind of evidence that needs to be gathered in order to demonstrate the contribution of public libraries to social capital.