This study was designed to investigate the behavioral factors that determine the effectiveness of branch engineering managers at the Naval Avionics Center (NAC) in Indianapolis. Data were collected using a survey designed especially for this study. Ratings of effectiveness variables were obtained from both engineers (subordinates) and the division manager (superior) for each branch manager. Correlations were run between these effectiveness variables and specific managerial behaviors as rated by engineers in each branch. Somewhat different sets of behaviors or critical skill areas were found to be related to three different sets of effectiveness variables. A composite picture highlights the importance of the branch managers' communication activities and identifies four communication functions crucial to the effectiveness of the branch manager. These functions are (1) Listening and Responding to Branch Managers, (2) Providing Guidance to Branch Members, (3) Encouraging Collaboration Among Branch Members, and (4) Communicating the Needs of the Branch. This empirical data can be used as input for designing management development programs, selecting engineering managers, and conducting performance appraisals.