Sub-municipal government is an instrument that complements traditional forms of citizen participation and as such contributes to the democratization of the decision-making process on local interests. The main task of sub-municipal government in Croatia is to serve as the consultation and communication mechanism within local units, allowing alternative representation of small communities’ interest, parallel with local councils. However, sub-municipal government has a rather weak position in terms of autonomy, financing, low transparency, size and other. Nevertheless, examples of some Croatian cities demonstrate the democratization potential of sub-municipal government. In this paper, a survey has been conducted in the city of Rijeka (third biggest in Croatia) with questionnaire being send to all of its sub-municipal units. The goal of the survey was to assess which roles sub-municipal units have. The results have shown that the role of sub-municipal local units as activators of local activities is the most developed one. The results are then used to provide guidance for further improvement of sub-municipal system in Croatia.