A technique for allowing isolated JAVA applications (“isolates”) to share data between themselves is disclosed. According to one aspect, a shared object region, to which multiple isolates may attach, is defined in memory. A shared class loader associated with the region is stored in the region in conjunction with the region's creation. Isolates that can access the region can invoke that loader. The region only comprises objects whose type is defined by a bootstrap class loader or the region's associated shared class loader. Runtime representations of classes defined by the shared class loader are stored in the region. Thus, the types of objects stored in the region are known to all isolates that attach to the region. Isolates attached to the region may enter the context of the region to access objects stored therein. Within the context of a shared object region, all allocation instructions automatically allocate to that region.