This book uses doctrinal and theoretical analysis to explain the meaning and role of conscience and unconscionability in private law. It shows how they appear most prominently in the context of equitable obligations and primary equitable and common law liabilities. The book tracks how their use reveals two major recurring moral concerns. Firstly, the prevention of unconscientious retention of the benefits afforded by legal rights. Secondly, that of the need to give effect to, or redress the negative consequences of a breach of a voluntary undertaking in certain circumstances. Where the limits of conscience are understood and respected, it can bring certainty and as such ensures the authority of private law. This is a fascinating study of little understood but crucial concepts in private law.