Current public participation methods are laborious, reach few participants and are ineffective at gathering usable information for planning. This situation leads often to mistrust and dissatisfaction in the process and outcome. This article identifies the critical conditions for meaningful use of public participation GIS (PPGIS) tools to support the making of master plan in Helsinki. With PPGIS tools, residents' insight of their living environment can be reached and utilized along the planning process. The results are divided to conceptual and empirical points. Whereas the conceptual points emphasize better understanding of the locus of the PPGIS tools in planning process, the empirical findings reveal new ways to study how residents' perceptions align with the plan proposal. Though new tools, data and analysis can support representativeness, independence, early involvement, influence and transparency, planners and residents need more understanding of the benefits of these tools. The study indicates that though planners found the collected data and the analysis valuable, they still lacked the skills and institutional motivation to use the data effectively. The results point out that when PPGIS tools can be integrated to the mainstream planning practices, the tools have the ability to evolve to a more comprehensive participatory planning support system.