This paper describes how and why the Inter-Agency Standing Committee (IASC) Guidelines on Mental Health and Psychosocial Support in Emergency Settings were developed. A brief overview about the need for the guidelines, as well as the context and background, are included. Also, a discussion on the process of developing them with an eye towards identifying key issues and obstacles, and the strategies used to manage these issues and enable constructive collaboration, is provided. Also included are the processes of building positive networks and relations across agencies and subfields.