The quasi-annual WHY Symposium on Policy Evaluation and Causal Inference is a symposium focused on methods and implementation of causal inference methods, organized by Austin Nichols. The 2027 Symposium is tentatively scheduled for January 6-7 in DC after the ASSA concludes. The WHY Symposium is devoted to the use of causal inference methods in policy research. The Symposium features talks on methods and applied papers on a variety of topics. Sessions with presentations and discussion are mixed with opportunities for informal mingling both on site and at nearby locations. See the Acknowledgements (p.19) in the Stata manual entry for hdidregress for some indication of the benefits of attending WHY symposia. Typically, attendance is capped at 40, and only accepted registrants may attend. There is no meaningful virtual or hybrid option, though we were forced to improvise for our inaugural 2020 symposium. Past symposia The first WHY Symposium, WHYKY in Kentucky, organized by Austin Nichols and Jose Manuel Fernandez, was co-sponsored by and the College of Business at the University of Louisville. The second WHY Symposium, organized by Austin Nichols in DC in 2022, was co-sponsored by and hosted by the National Academy of Social Insurance. The third WHY Symposium, in Park City in 2023, was organized by Adam Looney and Austin Nichols, and co-sponsored by and the University of Utah. The fourth WHY Symposium, in DC in 2024, was organized by Austin Nichols, and co-sponsored by . The fifth WHY Symposium, in Seattle in 2025, was organized by Austin Nichols, and co-sponsored by .