In his autobiographical account ‘My Life as a Lawyer’ Ole Lando wrote: ‘I set out to try and unify the substantive contract law in the EU. My efforts started in 1976’. These efforts were to lead to the publication of the Principles of European Contract Law (PECL) in 1995 (Part I), 2002 (Parts I and II), and 2003 (Part III). According to Hugh Beale it is that work for which Ole Lando is best known; and it is for that work that he is regarded as ‘one of the most influential figures in the development of European private law to date’. The present contribution therefore deals with these Principles of European Contract Law.