This study evaluated the Enhancing Relationships in School Communities (ERIS) Project which aimed to promote constructive conflict resolution (CR) in Australian primary school communities through professional development for core teams of three-five staff (n = 33 teachers). Twelve schools were randomly assigned to a full intervention (FI) group or a partial intervention (PI) group with seven and two days professional development respectively and equivalent levels of in-school support over 16 months. Teachers from the same schools who received no direct intervention (NDI) (n = 33) were comparison groups. Significant positive differences were found between the FI teachers and the PI and NDI participants in their use of CR steps and use of an integrative approach to conflict. At post-intervention the FI group participants' attitudes to conflict became most positive. While both FI and PI participants disseminated CR information to staff and students, the FI group reported higher levels of dissemination. (Contains 1 figure and 2 tables.)