The  monograph  considers  lobbying  as  an  integral  part  of  the  EU  political  system.  Special  attention  is  paid  to  justifying  the  concept  of  throughput  legitimacy  for  the  political system of the EU and functional role of interest groups in the decisionemaking  process.  The  author  examines  lobbying  possibilities  at  each  stage  of  the  legislative  process  and  revises  the  comitology  procedures  with  all  the  amendments  introduced  after the Treaty of Lisbon. The monograph shows that the process of politicization of  European integration demands further democratization of EU political system which is  proved  by  lasting  democratic  deficit  and  legitimacy  crisis.  In  order  to  resolve these  problems, it is necessary to improve the level of transparency of the decisionemaking  process and introduce lobbying regulation which is on the EU’s political agenda.