Advanced Distributed Simulation (ADS) is an enabling concept to support the networked interaction of models and real world elements resident at geographically dispersed sites planned for next generation simulation environments such as Joint Simulation System (JSIMS). In this paper we review the DEVS formalism and indicate why it provides the right framework to address many of the difficult technical issues that must be solved to enable ADS to provide infrastructures for distributed simulation. Then we address two of these issues in detail. The first issue addressed is the use of filtering and predictive contracts to reduce the tremendous amounts of data and control messages that must be transmitted in simulations. The second part focuses on scheduling and synchronization mechanisms for efficient parallel execution of such models.