We cannot yet predict large earthquakes in the short term with much reliability and skill, but the strong clustering exhibited in seismic sequences tells us that earthquake probabilities are not constant in time; they generally rise and fall over periods of days to years in correlation with nearby seismic activity. Operational earthquake forecasting (OEF) is the dissemination of authoritative information about these time‐dependent probabilities to help communities prepare for potentially destructive earthquakes. The goal of OEF is to inform the decisions that people and organizations must continually make to mitigate seismic risk and prepare for potentially destructive earthquakes on time scales from days to decades. To fulfill this role, OEF must provide a complete description of the seismic hazard—ground‐motion exceedance probabilities as well as short‐term rupture probabilities—in concert with the long‐term forecasts of probabilistic seismic‐hazard analysis (PSHA). > Operational earthquake forecasting is the dissemination of authoritative information about time‐dependent probabilities to help communities prepare for potentially destructive earthquakes. The status of OEF and guidelines for its deployment have been described in a comprehensive report by the International Commission on Earthquake Forecasting for Civil Protection (ICEF), which was convened by the Italian government following the L’Aquila earthquake disaster (Jordan et al. , 2011). The ICEF conceived of OEF not as a stand‐alone activity, but as one component of a larger system for guiding mitigation actions based on scientific information about the earthquake threat (Fig. 1). The proper role of OEF is to inform, but not prescribe, the response by end users to changing seismic hazards. The front end of an OEF system should be an interface for continually providing forecasting information that is timely, authoritative, and properly conditioned to serve multiple end users, including the general public. Figure 1. Schematic diagram of an operational earthquake forecasting system that provides probabilistic forecasting information (left side) through …