Ideally, all aid organisations would publish detailed information about their programmes, spending and impact, allowing us full visibility of the aid delivery network. But there are hundreds of thousands of aid organisations around the world, and only 230 agencies (albeit the biggest ones) regularly publish data in the International Aid Transparency Initiative (IATI) Standard. So, with such a mountain to climb, and limited resources, where should the IATI community focus its efforts? Alex Tilley looks at who is currently publishing IATI data and considers the pros and cons of supporting all those organisations funding and implementing aid projects to publish data, versus just the largest.