Governments, organizations, and schools around the world are committed to providing a safe and friendly learning environment for students. However, bullying, truancy, violence, discrimination, and addiction are still common in schools around the world due to students' maladaptive and deviant behaviors. While educators have focused on such issues over the past few decades, with the boom in internet use, the impact of adverse events in schools has expanded from offline to online, and this has become a globally important public health issue. In addition, adverse events continue to occur, even as educators work to intervene and prevent these events. Due to these issues, it is necessary to continue to explore the causes and effects of these maladaptive and deviant behaviors and the effectiveness of interventions over time. These findings will help governments, organizations, educators, and communities worldwide to address and prevent the occurrence of maladaptive and deviant behaviors in schools. Therefore, our journal presents a Special Issue on this topic. In this Special Issue, 18 articles have been included, covering editorials, research papers, systematic literature reviews, commentary articles, and more. We believe that this Special Issue reprint will contribute to understanding the reasons behind and counseling strategies for improving maladaptive and deviant behaviors in schools.