In many world regions vaccination of children is near universal, but there are still large gaps, and new vaccines are being developed that need to be explained and promoted. Numerous compelling stories about active collaboration between religious and non-religious bodies turn around vaccination campaigns. But where religious leaders are skeptical about the motivations of public health workers or suspicious of the vaccines, campaigns flounder. The World Faiths Development Dialogue, urged by GAVI, looked at gaps in coverage with an eye to new opportunities and a starting hypothesis that faith communities are engaged but far less than they could be. The research explores what more can be done and what it takes to build robust and effective new partnerships.