Abstract
This article discusses the findings of three field researches on the development of informal networks based on horizontal contacts, interpersonal trust and common professional identity. Specifically, it examines interaction of personnel from law enforcement and intelligence agencies involved in countering terrorism and crime that are officially assigned outside of their traditional jurisdiction. Taken together, based on the findings of the three different studies, it suggests a basis for the scalability of inter-agency networking from the local to the national and international levels. On the international level, the acceleration of communications and movement associated with globalisation leads officers to seek and share information through direct contacts with peers in other agencies to skirt formal liaison barriers. Building interpersonal trust emerges as a crucial variable in the success or failure of these efforts.