Plea bargaining is the primary, and unavoidable, method for resolving the vast majority of criminal cases in the United States. As more attention is paid to reform and changes in the criminal legal system, plea bargaining has also come into the spotlight. Yet we actually know very little about what happens during that process—a potentially complex negotiation with multiple parties that can, at different times, include prosecutors, defense counsel, judges, defendants, and victims. Using negotiation theory as a framework, we analyze why more information about the process itself can improve this crucial component of the system. More information—more data—would permit informed judicial oversight of pleas, improve lawyers’ capacities to negotiate on behalf of clients and the state, and increase the legitimacy of the bargaining between parties where one side tends to have far more resources and power. Without increased transparency, many of the players in the criminal legal system are just bargaining in the dark.