This paper argues that informal, intuitive, and unsystematic methods of operation are no longer adequate for the practitioners of mass communication. It presents a brief summary of the historical development of mass communication, followed by a general summary of mass communication research, relating mass communication to interpersonal communication and analyzing the process of information flow. Among the topics considered are: the nature of the communicator, the media and their audiences, and the effects and effectiveness of mass communication. Throughout, the paper emphasizes the need for more interaction between communication research and practice in order that theories and principles can be evaluated in the field. (RN)