Research suggests that a particularly important variable in determining success in public participation is the presence of a facilitator. Data from a study of 239 public participation case studies is analyzed using descriptive and statistical analysis to determine the impact on success of the participation efforts if a facilitator is present and whether or not internal versus external facilitators have a significant impact on success. The data suggest that facilitators have a positive impact on the success of public participation efforts and, in particular, that public participation efforts that use facilitators are more successful when the facilitator is a third-party intermediary (external) versus a member of the lead agency's staff (internal).