The starting point for a participatory model to policy decision making must be a reasoned justification for why this approach is being taken. In the case of Charlestown's openspace planning efforts, it was clear from this project's conception that the elected municipal planning community has the ultimate responsibility to decide upon which lands to acquire and protect as openspace. However, in their paper, "Public Participation and Local Environmental Planning: the collective action problem and the potential of social capital," Rydin and Pennington underscore the purpose for engaging the public in the formation of local policies, stating "A primary argument in favor of more participation suggests that the involvement of the public...provides information to the policy process. This information may relate to the public's preferences but may also be more specific, relating to local knowledge." When attempting to prioritize the importance of potential openspaces, it was clear that "the public holds key resources of knowledge that policy actors need to achieve policy goals." While more objective elements of openspace planning, such as the compilation of expert identified natural resources data, can be organized without necessarily engaging the public, information such as local significance and the contribution a site makes to Charlestown's sense of place must come from residents. Therefore, this was the primary purpose for engaging residents in a survey to identify specific locally important places for openspace preservation.

Another common practice of public participation in openspace prioritization is the employment of contingent valuation surveys to determine what types of land people are most willing to support financially. A recent, local study of this kind was completed by Steven Swallow of the University of Rhode Island for the town of Richmond, RI. This approach was not pursued for the Charlestown Openspace Prioritization Project because the Planning Commission was interested in identifying real places throughout the community that residents deem important for preservation. Furthermore, this economically based model cannot account for all of the complex factors that combine to form a resident's perception of the importance of a particular farm or view from a road in their community.