This collection of essays addresses some of the fundamental questions facing the law of contract and of unjust enrichment in the twenty-first century from a comparative perspective. Leading academics from Canada and the United Kingdom analyse the nature and development of the principles of unjust enrichment, their relationship with contract and fiduciary obligations and their impact upon traditional contractual doctrines such as mistake, undue influence, frustration and the assessment of damages. The text provides an insightful, contemporary and provocative examination of this fast-developing area of law.