1. It has been one of the most abiding points of interest of modern organizational research to study how well the programmatically intended formal structures of organizations describe what is going on within them, and what unintended, unprogrammed , and thus informal structures tend to accompany them.How do sociologists go about distinguishing the facts of formal organization from the facts of informal organization? There seem to be two things that matter in the ways this distinction is drawn. There is, in the first place, a certain scholarly tradition in which the distinction is rooted. It dates back to Pareto’s definition of rationality, Tönnies’ typology, Cooley’s concept of primary-group, and – tracing through the seminal achievement of the Hawthorn studies – the tradition is very much alive today. Being steeped in this line of scholarship allows a sociologist to claim his colleagues’ consent to the decisions he makes. In this way the distinction is a fact of life in sociological inquiry, and perceiving it correctly is a trademark of professional competence. Although this is undoubtedly a potent factor in many decisions, it does not furnish a clear-cut rule for the distinction.