Shifting from a single-site manufacturing facility to a multi-site enterprise enables a company to seize business opportunities by increasing production, specializing capabilities, and moving closer to target markets and low cost raw material sources. The supply chain of such a multi-site enterprise is complex as numerous interacting entities with different interests are involved. In this paper, we present a dynamic model of a multi-site chemical supply chain, which can serve as a quantitative simulation tool to aid decision-making. The model explicitly considers the entities and their interactions in various supply chain activities such as order acceptance and assignment, job scheduling, raw material procurement, storage, and production. Different policies, configurations, and uncertainties can be simulated and their impacts on overall performance can be analyzed. This paper describes the model and illustrates its application for decision support in a multi-site chemical supply chain. © 2009 IEEE.