Intelligent agent technology has evolved rapidly over the past few years along with the growing number of agent systems in various domains. Although a substantial amount of work in agent-oriented software engineering has provided methodologies for analysing, designing and implementing agentbased systems, recent studies have highlighted that there has been very little work on maintenance and evolution of agentbased systems. A critical issue in software maintenance and evolution is change impact analysis: determining the potential consequences of a proposed change. There has been a proliferation of techniques proposed to support change impact analysis of procedural or object-oriented systems, but to the best of our knowledge, no such an effort has been made for agent-based software. In this paper, we fill this gap by proposing a framework to support change impact analysis for agent systems. At the core of our framework is the taxonomy of atomic changes which can precisely capture semantic differences between versions of an agent system. We also present a change impact model in the form of an intra-agent dependency graph that represents various dependencies within an agent system. An algorithm to compute the set of entities impacted by a change is also presented. The proposed techniques have been implemented in AgentCIA, a change impact analysis plugin for Jason, one of the most wellknown agent programming platforms.