This article focuses on the third-party roles in a 2008 to 2010 assessment of the collaborative capacity of the U.S. Army Corps of Engineers (USACE). Within USACE, the effort was led by the Institute for Water Resources' Conflict Resolution & Public Participation Center. Third-party assistance was provided by a professional environmental facilitator under contract to USACE. Data were obtained through an online assessment tool (n = 230) and nine workshops. A national stakeholder Review Group and a cadre of internal liaisons to field personnel provided input at strategic milestones. The resulting collaborative capacity development recommendations are now being implemented.