Despite the importance of faculty diversity training for advancing an inclusive society, little research examines whether participation improves inclusion perceptions and belongingness. Integrating training and diversity education literature concepts, this study examines the effectiveness of training targeting microaggressions in six STEM (Science, Technology, Engineering, Mathematics) oriented departments at a research-intensive university. Reactions data collected at the end of face-to-face training suggested that participation generally increased inclusion understanding. Self-assessments on inclusion concepts collected from 45% of participants before and three weeks after training suggest participation increases perceptions of the importance of inclusion, microaggression allyship awareness, inclusive behaviors, and organizational identification. Compared to white men, women and minorities reported a greater increase in satisfaction with their department affiliation. While self-assessment results are exploratory and have limitations, analysis suggests that diversity training may enhance knowledge of microaggressions, allyship, inclusive behaviors, and belongingness perceptions. We provide insights for evaluating and implementing diversity training interventions.