The aim of this paper is to introduce a two-phased approach for supporting participatory decision-making and a Web data oriented architecture that will enable the implementation of the proposed approach. Combining Social and Government Data in a two-phased approach for enabling participatory decision-making. Understand public opinion refers to the ability of decision makers to understand what is the current opinion of citizens towards a specific decision. Predict public reactions refers to the ability of decision makers to predict what will be the public reaction on a decision.