The EU has long been committed to developing a common regulatory framework for different categories of workers across Member States. Over the years, that framework has expanded from its original focus on the free movement of workers to cover a broad range of issues, including non-discrimination legislation, the regulation of salaried work, worker protection in restructuring situations, and the legal treatment of atypical and flexible forms of work. In this regard, EU law now combines market integration principles with increasingly detailed employment rules, implemented through legislation, social dialogue instruments and case law. This Practice Note explores the regulatory framework applicable to different worker categories under EU law, focusing on the main legal instruments, the key concepts and protections they introduce, and the more recent developments affecting new and evolving forms of work. For information on: • EU social security coordination, see Practice Note: Social security coordination under EU law • free movement, see: EU free movement of persons (EU Law)—overview • non-discrimination legislation, see Practice