The dependability of component-based systems mainly relies on the ability to guarantee the safe collaboration of components. Many specification formalisms can then be used and we argue that such specifications should be organized through an appropriate contract model so that guarantees and possible violations can be better exploited. In this paper, we propose a versatile contract model that explicitly reifies the assumptions and guarantees of some behavioral specifications on component assemblies. We briefly illustrate the integration of executable assertions and we detail how Behavior Protocols can be integrated in the contract model.