This article discusses the relationship between the expert knowledge and the prospects of politicizing and democratizing urban planning. The term 'experts' refers mainly to urban planners, yet also includes architects, engineers and lawyers, who are specialized in planning. The article begins with a review of the critical literature on communicative planning, agonistic pluralism, agonistic planning and discussions on what needs to be done in planning focusing on the role of the expert knowledge. It argues that expert knowledge can gain different and multi-dimensional roles in urban planning processes, leading not necessarily to techno-management, yet contributing in their inclusiveness and conflict sensitivity. Encompassing both technical support and objective intermediation for local communities, it can both be utilized to build an agonistic space and help the communities better utilize the existing communicative/collaborative channels to voice their disagreements. By this way, it contributes in the politicization and democratization of planning processes. With this argument, the article also aims to challenge the strict distinction between 'the politics' and 'the political' as well as the related communicative-agonistic divide. The argument is supported by evidence from a case study on two informally built residential neighbourhoods in Istanbul, where there has been an active citizen opposition and involvement in a planning process.