To contribute to an understanding of the elements of good air traffic controller communication with the objective of providing recommendations to improve controller communication training, two studies analyzed team communication, ground-air communication, and ground-line communication. The simulated and live traffic analyses examined established and new controller teams drawn from three different experience levels. The design included team types made up of expert and intermediate controllers who had worked together at their control centers; and team types made up of experts, intermediates, and novices who had not worked together previously. A total of 24 participants in the Simulated Traffic Communication Analyses comprised of experts, intermediates and novices worked in teams of two controllers each on a total of six simulator problems over a period of 2 days. A total of 14 participants worked in 2-person teams of radar controller and radar associate controller in the live traffic analyses. Results of the two studies suggested that: (1) advanced communication training for en route traffic controllers should be embedded in the relevant training on those tasks that are primarily cognitive and operational; (2) a new emphasis should be placed on the functions of different types of communication within controller teams and between controller teams and other sectors and facilities; (3) the goal of en route controller communication training should be to provide controllers with an extensive repertoire of communication skills and techniques that the controllers can use on a selective basis to accomplish specific tasks; and (4) developmental controllers should be trained in the skills, and choices of communication strategies, that were demonstrated by the controllers in the top rated teams in this study. (Thirty tables of data and 27 figures are included.) (PRA)