We are developing an agent-oriented software development methodology, called Tropos, which integrates ideas from multi-agentsystem technologies and RequirementsEngineering research. A distinguishing feature of Tropos is that it covers software development from early requirements analysis to detailed design, allowing for a deeper understanding of the operational environment of the new software system. This paper proposes a characterization of the process of early requirements analysis, de ned in terms of transformation applications. Di erent categories of transformations are presented and illustrated by means of a running example. These transformations are then mapped onto a set of primitive transformations. The paper concludes with observations on the form and the role of the proposed transformations.