This chapter focuses on the characteristics of effective scientific and medical communication, expectations of effective communicators, criteria for authorship in science, role of professional communicators in science and medicine. Although quantitative measures of readability provide only limited insight, particularly when applied to technical discourse among experts such as in scientific and medical communication (SMC) subjective accounts corroborate these measures. Unfortunately, novice scientists and writers often mimic the poor writing examples that they find in the literature and thus perpetuate poor writing throughout SMC. The Committee on Science, Engineering, and Public Policy of the National Academy of Science, National Academy of Engineering, and Institute of Medicine of the National Academies note that different fields and professional societies have somewhat different conventions for the order of authors. The scientific and medical literature contains numerous accounts of and appeals to the role of professional communicators.