Learning how to be a successful systems engineer is entirely different from learning how to excel at a traditional engineering discipline. It requires developing the ability to think in a special way, to acquire the “ systems engineering viewpoint, ” and to make the central objective the system as a whole and the success of its mission. The systems engineer faces three directions: the system user ’ s needs and concerns, the project manager ’ s financial and schedule constraints, and the capabilities and ambitions of the engineering specialists who have to develop and build the elements of the system. This requires learning enough of the language and basic principles of each of the three constituencies to understand their requirements and to negotiate balanced solutions acceptable to all. The role of interdisciplinary leadership is the key contribution and principal challenge of systems engineering and it is absolutely indispensable to the successful development of modern complex systems.