This chapter describes the negotiation model adopted by the Customer and Supplier Negotiation Agents in the agent based architecture described in Chapter 2. The chapter is structured as it follows: in the first section the use of automated negotiation in modern market scenario is motivated; in the second section, starting form the contributions presented in the scientific literature, automated negotiation will be analysed and a taxonomy will be proposed. The third section is dedicated to the e-market context discussed in this book and in particular the impact of negotiation in manufacturing e-marketplaces will be stressed: its impact is strictly related to the electronic nature of e-marketplaces and to the supply chain coordination aspects of a make-to-order environment. Section four discusses the problem related to the negotiation performance evaluation. Finally, in section five we will introduce the developed negotiation model: after an overview of the agents involved in the process, the negotiation anal ytical model is presented.