A SIMPLE BUT EFFECTIVE communication model is described in this article. Commonly called the S-M-C-R model, it was originated by Dr. David K. Berlo, of Michigan State University, for use in a national training program in writing. The model consists of the four major factors in the communication process: a source, a message, a channel, and a receiver. Within each factor are a number of subfactors or variables of which the writer needs to be aware since they can influence the understandability of his material.