I study team decisions among physician trainees. Exploiting a discontinuity in team roles across trainee tenure, I find evidence that teams alter decision-making, concentrating influence in the hands of senior trainees. I also demonstrate little convergence in variation of trainee effects despite intensive training. This general pattern of trainee effects on team decision-making exists in all types of decisions and settings that I examine. In analyses evaluating mechanisms behind this pattern, I find support for the idea that significant experiential learning occurs during training and that teams place more weight on judgments of senior trainees in order to aggregate information.