The unprecedented growth of the internet and web-based applications has necessitated the deployment of intelligent agents to facilitate some of the tedious and time-consuming activities on the Web. Consequently, there is an increasing demand for agent-oriented systems, which are soon becoming large and complex. To support a systematic development of such systems, an agent-oriented software development methodology is necessary. This chapter focuses on the modeling phase of agent-oriented software life cycle and, presents an approach for agent modeling consisting of Agent Elicitation, Intra, and Inter Agent modeling methods. Agent Elicitation deals with identifying and extracting agents from “classes” in the real world. Intra Agent Modeling involves expressing agent characteristics such as goal, belief, plan and capability, whereas, Inter Agent modeling incorporates agent mobility and communication.