Breaking ceilings: Debate training promotes leadership emergence by increasing assertiveness.

To date, little is known about what interventions can help individuals attain leadership roles in organizations. To address this knowledge gap, we integrate insights from the communication and leadership literatures to test debate training as a novel intervention for leadership emergence. We propose that debate training can increase individuals' leadership emergence by fostering assertiveness-"an adaptive style of communication in which individuals express their feelings and needs directly, while maintaining respect for others" (American Psychological Association, n.d.)-a valued leadership characteristic in U.S. organizations. Experiment 1 was a three-wave longitudinal field experiment at a Fortune 100 U.S. company. Individuals (N = 471) were randomly assigned to either receive a 9-week debate training or not. Eighteen months later, the treatment-group participants were more likely to have advanced in leadership level than the control-group participants, an effect mediated by assertiveness increase. In a sample twice as large (N = 975), Experiment 2 found that individuals who were randomly assigned to receive debate training (vs. nondebate training or no training) acted more assertively and had higher leadership emergence in a subsequent group activity. Results were consistent across self-rated, group-member-rated, and coder-rated assertiveness. Moderation analyses suggest that the effects of debate training were not significantly different for (a) U.S.- and foreign-born individuals, (b) men and women, or (c) different ethnic groups. Overall, our experiments suggest that debate training can help individuals attain leadership roles by developing their assertiveness. (PsycInfo Database Record (c) 2025 APA, all rights reserved).