This in-depth review delves into the multifaceted realm of mass shootings and explores their epidemiology from a psychological perspective. The article presents a comprehensive examination of the prevalence, perpetrator and victim profiles, motives, and contributing factors associated with mass shootings. By investigating the intricate relationship between masculinity, domestic violence, military service, social media, fame-seeking, suicidal ideation, mental illness, and firearms, this article sheds light on the multifaceted nature of mass shootings. Moreover, it discusses the importance of implementing effective prevention strategies to address this growing public health concern. The findings from this review serve as a valuable resource for researchers, practitioners, policy makers, and the community at large, facilitating a deeper understanding of mass shootings and fostering the development of evidence-based solutions to prevent these tragic incidents. Expected final online publication date for the Annual Review of Clinical Psychology, Volume 20 is May 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.