We evaluated a Web-Based Emotional Intelligence Training (WEIT) program that was based on the four-branch model of emotional intelligence (EI) and which aimed at improving emotion perception (EP) and emotion regulation (ER) in future leaders. Using a controlled experimental design, we evaluated the short-term (directly after the WEIT program) and long-term (6 weeks later) effects in a sample of 134 (59 training group [TG], 75 wait list control group [CG]) business students, and additionally tested whether WEIT helped to reduce perceived stress. For EP, WEIT led to a significant increase in the TG directly after training (whereas the wait list CG showed no change). Changes remained stable after 6 weeks in the TG, but there were no significant differences between the TG and CG at follow-up. By contrast, ER did not show an increase directly after WEIT, but 6 weeks later, the TG had larger improvements than the CG. The results mostly confirmed that emotional abilities can be increased through web-based training. Participants' perceived stress did not decrease after the training program. Further refinement and validation of WEIT is needed.