SummaryOrder acceptance (OA) has a large inuence on the performance of an enterprise. On the one hand, always accepting an order when capacity is available may restrict the system to accept more protable orders in the future. On the other hand, rejecting too many orders leads to low capacity utilization and also has repercussions for future customer relations. In addition, accepting too many orders leads to an over-loaded production environment, where lead times increase and orders are delivered late. Most of these aspects of order acceptance decision-making can be handled by having proper negotiations with customers on order terms. However, this is a complex problem primarily because there are dierent actors who have various (conicting) interests, needs and objectives. Accordingly, to provide insight for the decision makers in the rms in order to develop proper strategies for order acceptance, developing appropriate models seems necessary.The objective in this research is to improve the order acceptance performance of a make-to-order multi-plant enterprise (MPE) by incorporating buyer-seller negotiations in its OA procedure with the main research question of How can the buyer-seller negotiation process contribute to the improvement of order acceptance performance in the multi-plant enterprise?For this purpose, we have developed an agent-based model to support order acceptance decisions in a multi-plant enterprise particularly using dierent negotiation settings.The research starts with literature review on order acceptance in general and negotiation in particular. A gap is identied in the OA literature: the major perspectives on the OA procedure rest on the underlying assumption that order terms are already determined which is not always tenable. In reality, order terms are usually specied by negotiation between the buyer and the seller and they are not predetermined. A negotiation-based order acceptance approach is consequently suggested in order to consider the whole activities in a negotiation process with three phases. The proposed process involves the initiation conditions for negotiation (pre-negotiation phase), the main interaction (negotiation phase) and the consequences of negotiation on the future decisions of the involved actors (post-negotiation phase). This negotiation process is a part of more general negotiation framework which is then extended into a negotiation ontology. The ontology introduces the main concepts and their relations in a negotiation problem. Next, the conceptualization of the order negotiation process in OA and the negotiation ontology are used in developing an agent-based model for buyer-seller negotiations in a case of multi-plant enterprise. The general assumptions and settings for model development are taken from a model have been presented by Behdani et al. (2010) for a lube oil multi-plant case study motivated by a real supply chain.In this research, the previous model is extended by incorporating negotiation between the ii enterprise and its customers on order terms. Final...