A study examined the communication climate of a graduate teaching assistant's (GTA) college classroom. Because the teaching role is often new to the GTA, establishing a communication climate may be a significant factor in classroom management. One section of a public speaking class taught by a new graduate teaching assistant at a large midwestern university was observed five times over a 2-month period. Results indicated that the GTA established a communication climate for his students that was open and supportive. Primarily, the climate was established through three factors: a highly-scripted daily routine; the interaction patterns that emerged among the students; and the general communication behaviors of the GTA. (Contains 17 references. Four diagrams illustrating the physical setting of the classroom, the seating chart, inside and outside clusters of students, and how the students grouped themselves for small-group activities are attached.) (Author/RS)