The impact of failing to develop a shared understanding of the requirements describing and constraining large, complex projects and programs with many, possibly distributed, stakeholders and suppliers is enormous. Traditional engineering methods provide little in the way of taming complexity when synthesising, analysing and communicating the requirements of such projects. The Behavior Engineering method, developed at Griffith University, and employed on a number of large, complex and nationally critical defence, aerospace, transport and government projects and programs addresses the problems of scale and complexity head on. The Behavior Engineering method is presented in this paper as an efficient and effective method for modeling, analysing, evaluating and communicating large requirements specifications comprising thousands of requirements as well as a method that facilitates the synthesis of requirements from operational scenarios. It is demonstrated through analysis of industry data, that Behavior Engineering facilitates the development and communication of a deep, accurate and holistic understanding of the system needs, significantly reducing the risk of failure to capture and preserve intent in the development of large and complex systems.