Industrial relations can be defined as the management of labour problems in an industrial society. Implicit in such management is the development of theories, techniques, and institutions to resolve the conflicts arising from work relations. These conflicts resuit from the permanent interaction of management efficiency, worker protectivism and the public policies developed by the State. The two processes that corne into play because of this inevitable interaction between management efficiency (whether at the level of the organization or society in gênerai) and the need for worker protectivism are human resource management and the establishment of working conditions, which in North America is called «labour relations». By «human resource management» we mean ail the activities or programs promoted by organizations and the State to acquire, maintain, develop, deploy and use effectively the persons doing or susceptible of doing useful work. And by «labour relations» we mean all the phenomena and activities related to the establishment of the rules for work. These rules are of two types: the substantive rules, which determine working conditions and the procedural rules, which determine the steps to be taken to change or apply the substantive rules. These two basic processes bring together three agents: the organization and its managers, the employees and their work society (union), and the State. The latter is involved in human resource management through its policies which seek to correct the imbalances in the labour market. It also adopts policies for the purpose of establishing minimum conditions for wages, hours of work, health, safety, and job discrimination. The State also determines the legal framework and the rules for the two other agents. Finally, since the State itself is an employer, it must like other employers develop a human resource management system and set the working conditions for its own employees. If the empirical presentation developed previously is now examined from an analytical or academic viewpoint, we see that industrial relations include three areas of study: human resource management, labour relations, and public policies on work. Also, when the Systems approach is applied to industrial relations, each of the agents is seen to have goals, values and even a certain degree of power, which allow them to organize, and to evolve their own philosophies. The interaction of the three gives rise to two types of activity that convert «inputs» to «outputs». Among the «outputs» are the turnover of personnel, absenteeism, worker attitudes, productivity, management rights, working conditions, and conflicts.