Eff ective school disciplinary systems-the philosophies, policies, and practices used to create safe schools that are maximally conducive to learning for all students-are necessary to ensure that schools maximize student opportunity to learn. In the fi rst edition of this handbook, Skiba & Rausch (2006) identifi ed four core goals of any school disciplinary system. First, discipline is intended to ensure the safety of students and teachers, preventing incidents that could threaten the safety of students or staff . Second, eff ective discipline creates a climate conducive to instruction and should improve academic outcomes by increasing the amount and quality of time teachers can spend teaching, rather than responding to behavioral disruptions (Brophy, 1988; Wang, Haertel, & Walberg, 1997). Th ird, from a purely behavioral perspective, a discipline system can be called eff ective only if it actually creates a change in student behavior over time, reducing rates of negative behavior and hopefully increasing prosocial behavior toward peers and adults (Alberto & Troutman, 2013). Finally, systems of discipline teach students the skills they need to succeed in schools and society.