Modular connections have been developed for use in seismic-resistant steel moment frames. The connections are configured specifically for optimal seismic response through the use of a steel casting process. The impetus for developing these connections is the recently discovered susceptibility of steel special moment frames during earthquakes. Major features of the modular connections are the minimization of stress/strain and the removal of the field weld from the critical cross-section. To date, two prototypes had been fully developed: (1) a panel zone dissipator modular node (PZ-MN); and (2) a bolted modular connector (MC). The PZ-MN dissipates energy through stable panel zone yielding without column kinking and weld distress; the MC dissipates energy in a variable-arm connector that minimizes plastic strain demand and eliminates prying forces. The prototypes were developed through a comprehensive analytical program using nonlinear finite element (FE) analysis. Full-scale prototypes were cast and tested under the FEMA-350 protocol. These connections exhibited stable energy dissipation and remarkable ductility.