The Aid Transparency Index assesses more than one agency for some large donors (EC, France, Germany, Japan, UN, U.S. and the World Bank) with multiple ministries or organisations responsible for significant proportions of ODA. We have opted to maintain the disaggregation of agencies for several reasons. First, no two agencies from the same donor country or organisation in the Index score the same. There is often wide variation in the amount of information made available by different agencies in a single country or multilateral organisation. Second, agencies often retain a large amount of autonomy in deciding how much information they make available and have different publication approaches, and should therefore be held accountable for them. Third, it would be unfair for high performing agencies within a country or organisation to be pulled down by lower performing agencies, and similarly lower performing agencies should not have their poor performance masked in an average score. Finally, it is unclear how we can aggregate agencies into a single country or organisation score in a way that reflects wide variations in performance. It would be necessary to take into account the proportion of a country’s aid delivered by each separate agency in order to create an aggregate country ranking that fairly reflects that country’s level of aid transparency and this information is not always available.