One of the most important lessons learned by GRECO, throughout its years of operation, is that the collection of first-hand information during on-site evaluation visits (a fundamental feature of GRECO's modus operandi) contributes significantly to the quality of evaluations. On-site visits are a major asset for the credibility of the whole process in that they enable evaluation teams to hold thorough discussions with domestic key players (including representatives of civil society), to request additional information on-the-spot, and to shed light on often blurred and contentious issues.