Holds a Laurea in political science from Torino University (1963), a Masters in mathematical economics from Moscow State University (1967), and a Ph.D. in economics from the University of California at Berkeley (1973).
In the ’70 Mr. Costa served as senior economist in the United Nations in New York.  In 1983-87 he was Under-Secretary-General at the Organization for Economic Cooperation and Development (OECD), in Paris. He concurrently was a Member of the IMF/World Bank Interim Committee and of the G-10 Group.
Between 1987 and 1992 Mr Costa was Director-General for Economics and Finance at the EU Commission, and EU Financial Sherpa for the G7 summits. In 1994 he was appointed Secretary-General of the European Bank (EBRD), in London. In 2002 Kofi Annan named him Director General of the UN Office on Drugs and Crime (in Vienna), with the rank of Undersecretary General, for an unprecedented double mandate that ended in September 2010. 
At present Mr. Costa is the Editor-in-chief of the Journal of Policy Models, the fastest growing scientific periodical in applied econometrics published by Elsevier Inc.  He is also the author of Checkmate Pendulum (Moringa AEF 2015), a fictional representation of the growing collusion between governments, finance and organized crime – translated into Italian as Scaccomatto all’Occidente (Mondadori, 2016).  In 2017 the book was awarded the Cerruglio Literary Prize.