Agent-oriented software engineering (AOSE) is an approach to construct software systems based on the agent paradigm. An agent can be thought of as an autonomous and social entity, which can communicate, coordinate, and cooperate with other agents to achieve goals. The agent paradigm offers useful abstractions to design today`s complex networked applications.Several AOSE methodologies have been proposed so far, each one providing its own modeling language and analysis techniques. Efforts toward unification of AOSE methodologies and the definition of standards are in progress, in parallel with research to address challenging issues, such as designing software with autonomic properties.