Modelling and simulation permeate all areas of business, science and engineering and increasingly complex simulation systems often require huge computing resources and data sets that are geographically distributed. The widely adopted platform for building distributed simulations is the High Level Architecture (HLA). Deficiencies associated with HLA have been well discussed in the literature. The advent of Grid technology enables the use of distributed computing resources and facilitates the access of geographically distributed data. In this paper, we propose a framework for executing large-scale distributed simulations using Grid services. The framework addresses some of the deficiencies of HLA, including dynamic discovery and resource utilization. End-users can construct large-scale distributed simulations using this framework with ease.