As it transitions to democracy from a history of authoritarianism, Croatia's interest group system is a work in progress. It is slowly moving from a fluid, informal, and behind the scenes group system to one more institutionalized, with wider participation, and some transparency of group activity. In this article, we explain the evolution of Croatia's interest group system. The main argument is that specific features of institutional design and structures have very much influenced political advocacy behaviour and lobbying strategies of both informal and organized interests.