This paper analyzes the concomitant link between the evolution of purchasing policy and the evolution of supply chain management. The duality of the mode of coordination of the suppliers depends on the relationship between the architect and the first-tier suppliers, according to the strategic degree of their competence. The contribution of this paper is to illuminate the plasticity, the adaptation of the purchasing strategy. The purchasing strategy therefore adapts to the nature of the equipment or systems outsourced, the stakes and expectations are not at all the same. The more complex the product manufactured by the subcontractor, the more the purchasing strategy will seek the mastery of a particular skill. The more standard the product, the more the purchasing strategy aims at reducing costs. The purpose of this paper is twofold. We will show, on the one hand, that there is within the same productive organization a duality of modes of coordination, On the other hand that there is an interaction between the purchasing strategy and these different modes of coordination.