On Monday, August 12th, 2019, 55 attendees joined us for the 12th USENIX Workshop on Cybersecurity Experimentation and Test (CSET ‘19) in Santa Clara, California. CSET, one of the USENIX Security Symposium’s co-located workshops, welcomes work in the broad categories of “cyber security evaluation, experimentation, measurement, metrics, data, simulations, and testbeds”—that is, research about research tools, data, and methods. The purpose of this article is to share our experi- ence chairing CSET ‘19, and to highlight this year’s papers.