Companies are increasingly shifting from single-site manufacturing to multisite operations to tap into the vast business opportunities offered by globalization. The supply chain of such a multisite enterprise is complex, involving numerous interacting entities with various roles and constraints, resulting in complex dynamics and complexities in decision making. This complexity motivates the development of simulation models of the supply chain that can capture the behavior of the entities, their interactions, the resulting dynamics, and the various uncertainties. In this article, we present a dynamic model of a multisite specialty chemicals supply chain that can serve as a quantitative simulation and decision support tool. The model explicitly considers the different supply chain entities and their interactions across various activities such as order acceptance and assignment, job scheduling, raw material procurement, storage, and production. It has been implemented as a dynamic simulator in Matlab/Simulink, called the integrated lube additive supply chain simulator (ILAS). Different policies, configurations, and uncertainties can be simulated in ILAS, and their impacts on the overall performance of the supply chain, such as customer satisfaction and profit, can be analyzed. The capabilities of ILAS for decision support are illustrated using several case studies.