Requirements regarding participation by the public in planning and decision making functions of Metropolitan Planning Organizations have become more detailed over the past several decades by adding more groups and individuals to the list of those who should be included in agency planning efforts. This increased emphasis on public participation in MPOs makes the design and selection of particular participation mechanisms by MPO planning staff an important subject for study. The extant literature on public participation takes a view of the planner as one who is able to interpret the existing technical, social, and political requirements of a planning task and match them with the appropriate public participation mechanism. However, this view of the planner overlooks his or her own understanding of the role of the public in agency decision making. This dissertation employs Grid-Group Cultural Theory to explore how a planner's worldview impacts their selection of particular public participation mechanisms. Data were collected using an online survey instrument and analyzed using multinomial logistic regression. Findings indicate that those planners who held a hierarchist worldview were less likely than egalitarians and individualist planners to select mechanisms that are more intensive (in their requirements for communication). In addition, the research finds that factors internal to the MPO including the budget, project schedule, political priorities, the type of projects, safety issues and agency priorities also have an impact on the mechanisms for public participation selected by MPO planning staff.