The Columbine High School shooting in 1999 prompted school officials and policy-makers to create and implement programs and policies that would prevent violence in school and ensure school safety. Ten years have passed since the Columbine shooting; however, debates concerning risk factors for the shootings continue to ensue. The focus of this article is to examine the Columbine school shootings within the context of Bronfenbrenner's (1994) ecological systems analysis. We examine the most commonly identified risk factors, which operate within five systems levels: chrono-, macro-, exo-, mesa-, and microsystems, and draw implications for school-based practice and policy. (C) 2010 Elsevier Ltd. All rights reserved.