Developing requirements from a group of analysts and system users is a difficult task. In addition to the usual problems of individual requirements acquisition, group requirements acquisition entails conflict detection, resolution generation, and resolution choice. In essence, requirements must be negotiated. In this paper, we summarize our model for requirements negotiation and its automated support. The model calls for the independent representation of user requirements followed by their negotiation. The model centers around three themes: user participation, resolution generation, and negotiation records. To support these themes, we have built a tool, called Oz, which provides: (I) automated methods for conflict detection and resolution generation, (2) an interactive resolution choice procedure, and (3) records of the negotiation process. This paper overviews our negotiation method and tool support.