Leadership self-efficacy (LSE) is widely known to yield positive performance outcomes, but how does LSE affect leaders’ development? Is high LSE a boon or a pain for leaders attending a leadership training program? Do “cup-full” (i.e., high LSE) leaders benefit from training, and if so, how? Using a sequential exploratory mixed-methods, we explore how “cup-full” vs “cup-empty” leaders respond to global leadership training and its effect on observer-rated performance improvement. In Study 1, qualitative findings (n=100) reveal that “cup-full” and “cup-empty” leaders respond to the training content in one of three ways: 1) conversion (switching from leadership practices to new practices), 2) reinforcement (leadership practices are strengthened), or 3) resistance (rejecting new practices), resulting in six learner profiles, These profiles uncover different types of “cup-full” leaders, some of whom benefit from training. Study 2 employs fuzzy-set qualitative comparative analysis (fsQCA) to analyze time-lagged quantitative data from 110 leaders and 238 observers to validate the six learner profiles and examine their relationship with post-training observer-rated improvements in leader performance. Results show that both “cup-full” and “cup-empty” leaders who experience “conversion” during training exhibit improved observed-rated performance. Our study demonstrates that while high LSE can impede learning, leaders with high LSE can be “converted” and persuaded to learn.