We are developingan agent-oriented software development methodology, called Tropos, which integrates ideas from multi-agent system technologies and Requirements Engineering research. A distinguishingfeature of Tropos is that it covers software development from early requirements analysis to detailed design, allowing for a deeper understandingof the operational environment of the new software system. This paper proposes a characterization of the process of early requirements analysis, defined in terms of transformation applications. Different categories of transformations are presented and illustrated by means of a runningexample. 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.