Soul is an object-oriented framework for object support, on which specific object-support operating systems (called “subsystems”) such as SOS, Comandos, or Cool, can be built and coexist. The Soul framework comprises a Nucleus (object-oriented microkernel), and a Generic Run-Time (GRT, an object-oriented toolkit of object-management object types and classes). A new subsystem is built by reusing, and extending, the existing GRT classes. Each subsystem constructs its own virtual machine. Separate applications in each subsystem communicate by sharing objects (including over time, with persistent objects). Since all subsystems share the same basic object mechanisms, we also have some hope for sharing across subsystems.