Conventional interconnect is rapidly becoming a critical issue in the realization of VLSI systems. Large silicon systems are especially limited by the bandwidth of available interconnect and the number of pinouts presently available. Optical I/O technology promises to provide relief from the pinout problem and to enhance performance significantly. Power requirements, interconnect flux, and noise immunity of metallized interconnects and electro-optic links are compared. Several alternatives for optical clock distribution and optical fiber interfacing are discussed. An architecture for an ultralarge electro-optic switch using optical interconnect is presented. The low noise characteristics of optical interconnect allow the use of novel synchronization circuitry that is both fast and compact.