Empirical studies of organized crime and criminal violence have been limited by a dearth of high-quality data on key attributes of violent criminal organizations including their structure, where they operate, what activities they engage in, and how they relate to one another. This project aims to fill this gap for Mexico and develop techniques that can be replicated elsewhere in Latin America.We are combining methods and sources, from hand-coding data to scraping and processing entire archives to interviewing knowledgeable local actors. A public platform will make updated data, procedures, and analyses transparent and available to all. Users will be able to download panel datasets on the activities and locations of criminal groups and their factions, disaggregated by source; visualize their evolution and relationships with other criminal groups through time; and read analysis that compares and validates existing sources and methods. This project is supported by the Center for U.S.–Mexico Studies at UCSD’s Global Policy School, the Empirical Studies of Conflict Project, and the Mamdouha S. Bobst Center for Peace and Justice at Princeton University