What does it mean to consent? Consent is an essential component of contracts, yet its part in contract law is obscure. Despite its importance, there is no independent doctrine of consent; rather, it plays a key, but ill-defined role in assessing doctrines such as assent or duress. This Article addresses this significant omission in contract law by disassembling the meaning of contractual consent into three conditions: an intentional act or manifestation of consent, voluntariness and knowledge. This Article argues that consent can only be understood relative to these three conditions. Accordingly, consent is not merely a conclusion but a process and a dynamic that depends upon a variety of factors, including the relative blameworthiness of the parties, their relationship, third party effects and societal impact. This Article, through an examination of classic and modern cases, demonstrates how the concept of relative consent provides a coherent framework for understanding contract law.