This chapter addresses how companies and regulators involved in complex system operations can create antecedents to error. Many of the antecedents relating to equipment design and organizational antecedents apply to regulator antecedents as well. Designers, regulators, companies, or operators themselves may determine the number of operators needed to operate the systems. Regulators may establish and enforce rules governing system design, system operation, maintenance, and personnel qualifications. Initial training should describe the system, its components and subsystems, their functions, normal and non-normal system states, and general company policies and operating procedures. Whether independent overseers of systems or elements of them, regulators provide a degree of oversight of most complex systems. As the pace of technological change has increased, regulators have found it increasingly difficult to maintain the necessary expertise to properly evaluate the system and the procedures needed to operate them.