Abstract This paper proposes a method which assists the firms for cooperating inmake-to-order production. We especially focus on the operational decision levels ofmanufacturing companies : the forecast scheduling and the real-time scheduling. Themethod organizes a production process which is distributed over several companies,by lowering the production stocks with the aim of decreasing production costs. In theselected approach, the global organization is achieved progressively by a set of coop-erations between pairs of actors of the supply chain. We study in particular the cus-tomer/supplier relationship for which the cooperation process concerns the attributesof the orders transmitted by the customer to the supplier. We assume that the relationis governed by a cooperation contract which defines a more contractual framework tothe cooperation between the decision-makers. Our objective is to design support toolsthat assist them during this cooperation process. 1 IntroductionMore and more often, the diversificationof their productionor the specialization of theirtradeinduce the companies to collaborate with numerous partners, in the context of networks so-called supply chains. New communication and information technologies increase the qualityand the frequency of the data exchanges and allow to ensure the coherence of informationwhich are shared between different actors. Nevertheless, they do not solve the coherenceproblembetween thelocaldecisions ofeach partnersand theglobalorganizationofthesupplychain. Thus, each actor is free to change at any moment a decision, possibly inducing a globalorganisational instability.To counteract this problem, the decisional autonomy of each actor needs to be specifiedin order to improve the global stability of the decisions. For this purpose, we suppose thatthe actors adopt a cooperation process in which a local decision, that affects the organizationof external companies, should be first negotiated, in the aim of increasing the lifetime ofthe decision. In the same way, any change of a local decision that may have impacts on theexternal partners, induces its author to renegotiate with his partners in order to achieve atrade-off which satisfies the community. In the following, the set of partners involved in thecooperation is called a business coalition.In the area of production systems, cooperation processes may have a lot of advantages.First, they allow a better tension of production flows, a better adaptation of the workingcapacities, and a better stability of the organization of the business coalition. So, they inducea global reduction of the production costs. On the other hand, the cooperation processes allow