This paper focuses on agent-based approach to study the relationship between the individual behavior of participants and the overall development of a virtual community, to help people to better understand the interactive process, forecast and manage the community development. In this paper, we first analyze the strengths of agentbased approach and the features of virtual communities. We argue that agent-based modeling and simulation approach is well suited to study virtual communities. We then build an agent-based model for virtual learning communities (VLCs). Each participant in VLCs is modeled as an agent with cognitive and social characteristics. The interactive activities are decomposed into four modules: registration module, activation module, action module, and adaptation module. A discussion of general observations of the community behaviors and managerial implications is presented based on series of comparative simulations.