This data paper reviews the experimental research on fully restrained beam-to-column connections for steel moment-resisting frames (MRFs) over the last 50 years worldwide and presents an experimental database consisting of 100 tests with an emphasis on those exhibiting inelastic panel zone behavior. The collected data, which is organized in a consistent format, includes full digitized histories of the local panel zone shear force-shear distortion as well as the global force-displacement hysteretic diagrams of each experiment. In most cases the original data was only available in paper format. The gathered dataset suggests that the existing panel zone models that are currently used for the seismic design of steel MRFs deviate, in some cases considerably, from the measured response quantities of an actual panel zone. These involve the panel zone stiffness and shear resistance at selected inelastic shear distortions of interest to the engineering profession. The assembled inelastic panel zone database provides ranges in which post-Northridge beam-to-column connections, which exhibit considerable inelastic deformations within the panel zone web, may achieve lateral drift demands larger than 4% without experiencing premature fracture. The assembled dataset constitutes an important source for validation of continuum finite-element models that could aid the simulation-based engineering design of steel MRF beam-to-column connections designed with a balanced design approach. The database is made available to the engineering and research communities through a publicly available data repository. (C) 2021 American Society of Civil Engineers.