The starting point in this book is the need to apply the conflict-of-laws rules to employment contracts ocarried out within the framework of posting to another Member State. It discusses the specific conflict-of-law rule provided for in the Posting of Workers Directive, which repeals the general conflict-of-law rules provided for in the Rome I Regulation. This rule imposes the application of the rules of the host state belonging to the so-called hard core, in order to provide the posted worker with equal protection in the country of posting. It also discusses the derogation of the above conflict-of-law rule, which is justified when the posted worker benefits from more favourable terms and conditions in the sending country. This follows from Article 3(7) of the Directive, which provides for a principle of advantage. The application of this principle requires a comparison of the terms and conditions of employment granted to the worker in the sending State with those guaranteed by the law of the host State. The book analyses the principle of favourable treatment in the context of minimum rates of pay. It approximates the method of comparing the contractual terms and conditions of employment in the sending country with those guaranteed in the host country. It also indicates how to determine the appropriate legal basis for posted workers' claims in litigation. Furthermore it discusses the possible impact of the choice of jurisdiction on the application of the favourability principle.