This paper aims to draw together the evidence-based advocacy experience of five national programs focused on developing public access information and communications technologies (ICT) via public libraries as grantees of the Bill & Melinda Gates Foundation's Global Libraries Initiative. The authors describe a common approach to strategic advocacy and to impact planning and assessment. They then outline the experience of each program in using a range of evidence to help meet specific advocacy objectives. They give particular attention to how each program is using specific evidence to convince key players of the importance of public access ICT provided by public libraries in meeting the objectives of the key players. This collective experience shows that when advocating at the national level, statistical data and empirical evidence can demonstrate that public libraries contribute to stakeholders' goals. Such data can include technology skills that users have gained as well as how users improve their businesses, become better educated, and access government services. Common denominators from the programs include a disproportionate positive impact achieved (or anticipated) in rural communities and on relatively disadvantaged groups such as older workers, old people and unemployed people. Both the general approach to evidence-based advocacy described and the specific messages about targeting advocacy efforts on key players and on the service users who are most likely to benefit from public access ICT are of potential value to anyone planning a national, regional or local advocacy program focused on public libraries and their services. As the paper deals with global library advocacy issues, and impact planning, it is hoped it is a step towards more measurable social impact for libraries. This is the first full public report of the Global Libraries approach to evidence-based advocacy as conducted in the five countries represented in the paper. It is part of a steadily growing body of knowledge being amassed by Global Libraries about effective provision of public access ICT via public libraries in a range of countries. © 2011, Emerald Group Publishing Limited