Staged circuit switching (SCS) is a message-switching technique that combines a new protocol with new communication hardware. Protocol and hardware are designed specifically for networks that are intended to function as integrated, general-purpose MIMD machines, i.e. for "network computers". The SCS protocol is a form of circuit switching that degrades automatically into packet switching when unavailable output lines make further extension of a partial circuit impossible. The SCS hardware uses a front-end crossbar switch to multipex some small number of communication channels among all of a given node's incident links. Together, hardware and protocol represent an attempt to convert spare bandwidth into lower network delays. They also allow experimentation with networks that reconfigure themselves dynamically in response to measured traffic patterns. We compare SCS to packet switching, circuit switching and the "virtual cut-through" protocol of Kermani and Kleinrock, and discuss an SCS implementation designed for the SBN network computer.