The EdResearch for Action "Overview Series" summarizes the research on key topics to provide K-12 education decision makers and advocates with an evidence base to ground discussions about how to best serve students. This overview brief discusses the causes and effects of chronic absenteeism and three tiers of evidence-based practices to reduce it: (1) Reaching all students with broad-based and preventative supports; (2) Targeting students with signs of risk; and (3) Responding to chronic absenteeism with coordinated supports. Ineffective practices to avoid are also provided.