Although the private law scholarship has devoted great efforts to analyze good faith in contracts and its scope, few of them offer a philosophical-legal basis for its inclusion in the execution of contracts. This article proposes to ground this notion with the help of the conceptual tools from Hegel’s Philosophy of Right. Good faith will thus will qualify as a legal device that incorporates into the contract the normative content that the free will generates in the different moments of its development. Thanks to good faith the contract could count as an adequate instrument in the sphere of what Hegel calls ethicality. In this sense, the paper proposes to assume good faith as the mechanism binding altogether the normative content of the contract. On the one hand, it will assimilate the express terms of the parties –qua person and subject– in the spheres of the so-called abstract law and morality (internal good faith). On the other hand, it will incorporate the set of normative attitudes or practices of the members of a society –qua market agents– proper to ethicality (external good faith). Consequently, the contract has a two-tier normative adjustment. One relating to what performance is due and the other relating to how that performance must be satisfied. Thus, this article does not assume that good faith can generate obligations beyond what is stipulated in the contract for the parties, because it has an adverbial function.