The relation between competition and regulation has always created tensions and opportunities. The existence in certain markets of network effects, market failures or imperious reasons of general interest make regulation crucial in certain cases. Energy, telecommunications, pharma, postal services, or transport are clear examples of this. Nevertheless, the influence of lobbies and regulated industries in those sectors can affect regulation in a direction that is not coherent with competition law principles and general interest protection. The seminar will deal with the principles that govern the relation between competition and regulation and the different possibilities to address the problems that the agencies usually face.