This textbook focuses on the interrelationships between economic elements and legal principles with regard to business and company law. Three jurisdictions are taken into consideration: US, UK, and Italian law (the last of which was chosen as a “prototype” of continental European legal systems). The economic elements underlying business and company law are actually common to the three legal systems and, consequently, their legal principles and rules are similar despite one jurisdiction (namely, Italy) being based on civil law and the other two on common law. Their similarities are also due to the historical origins of the legal instruments that are covered by the book: partnership law dates back to the Romans, while company law can be traced back to English law. Roman law and English law have influenced, respectively, partnership law and company law around the globe. The book addresses the following topics: proprietorship law, partnership law and company law. For each topic, it first identifies the economic and legal elements that are shared by the three jurisdictions, then explores each one separately to highlight the differences. The textbook is based on over thirty years of research on business and company law conducted by the author in Italy, the UK and US and more than fifteen years of teaching this subject to international students at Luiss G. Carli University of Rome as part of its Bachelor of Economics and Business program.