The Washington Group Questions on Disability are rapidly emerging as the preferred data collection methodology by the global community for national data collection efforts on disability. However, more and more development and humanitarian actors are now using the methodology in their own data collection efforts. This is beyond the original purpose of the questions, which was to generate usable data for governments. Leonard Cheshire and Humanity & Inclusion, two international charities focussed on disability and inclusion, have worked together to share learnings of recent research studies. These studies aim to understand how the Washington Group Questions (WGQ) have been used by development and humanitarian actors and the impact of using the methodology. This summary report outlines the key findings, analysis and conclusions about the application of the Washington Group Questions in a range of contexts. The report concludes with a number of recommendations for different stakeholders.