Modular connectors are being developed for use in seismic-resistant steel moment frames. The connectors are engineered specifically to meet performance requirements corresponding to optimal seismic response. The versatility in design required to accomplish this task is not readily available with traditional rolled shapes. Thus, the designs rely on advancements in materials and casting technology to create connectors specifically configured for seismic performance. To date, three modular connection configurations have been developed: (1) a semi-rigid modular bolted connector for partially-restrained frames; (2) a superelastic post-tensioned connecting system; and, (3) a cast modular node for moment-resisting frames. Trial designs have been developed for each of the three configurations and an analytical program has been initiated. Alpha prototypes for two of the concepts have been designed. One prototype has been created, and experimental work is underway.