In this chapter, we use the Chemical Reaction Metaphor (Banatre & Le Metayer, 1990, 1993, 1996) to model the interactions among program units, including the agents, clients, servers, and databases, in a multiagent-based e-learning system. Through case studies, we demonstrate that the Gamma language (Banatre & Le Metayer, 1990; Le Metayer, 1994) is suitable for specifying a multiagent system, particularly, because an agent’s properties, such as autonomy and mobility, can be captured concisely. The use of the high-level specification paves the way for solving architectural-design issues in building an e-learning environment. The Gamma specification of an agent system can be implemented in a hierarchical running environment, which is composed of nodes in different levels of a tree. Interactions among agents can be implemented in a unified mechanism for synchronization.