The term "intensive intervention" is not commonly understood, and variations abound in the literature regarding both its definition and implementation. This document introduces and describes the data-based individualization (DBI) process, a framework for addressing the needs of students who require intensive intervention in academics and/or behavior. DBI involves a dynamic, continuous interplay between assessment and intervention. It is a research-based method for individualizing validated intervention programs to improve outcomes for students with the most severe and persistent learning and/or behavior needs. Although the intended audience for this document includes anyone interested in learning about intensive intervention and DBI, it assumes a basic understanding of multi-tiered systems of support, such as Response to Intervention (RTI) and Positive Behavioral Interventions and Supports (PBIS), which form the foundation upon which intensive intervention is typically implemented. The information in this document is organized according to these three key questions: (1) Who needs intensive intervention? (2) What is the National Center on Intensive Intervention's approach to intensive intervention? (3) How is intensive intervention delivered?