Modern society is a society of organizations, as these human forms of grouping have become the usual way to attain most of the important objectives of people and the whole society. This course intends giving an updated explanation of the reality of organizations, considered as human extensions of obtaining difficult objectives, and emphasizing the communicational issues. The starting point of the research is the social history of organizations, from the appearance of factories and their expansion in the first industrial revolution. Then we could pay attention to the generalization of the companies within the industrial maturity and make a special reference to the situation in the new information societies, with the appearance of organizations as a network. It will also intend surveying the theories of organizations, from the classical views to the new institutional theories. We have also set out to obtain a better understanding of the focal issues of organization: the main roles, the social structure, the culture and the physical structure. Finally, the basic problems of organizations are surveyed: the participation proposal, the motivation, the communicational processes and the changes that new technologies are introducing in the future of work. In all these fields, during the last few years, sociology has been contributing rationalizations and proposals that are necessary to consider.