Book excerpt: This book places youth violence within a Routine Activity Ecological Framework. Youth violence, specifically youth exposure to community violence and youth perpetration of violent behaviors, occur within various contexts. Ahlin and Antunes situate their discussion of youth violence within an ecological framework, identifying how it is nested within four mesosystem layers: community, family, peers and schools, and youth characteristics. Contextualized using an ecological framework, the Routine Activity Theory and Lifestyles perspective (RAT/LS) are well suited to guide an examination of youth violence risk and protective factors across the four layers. Drawing on scholarship that explores predictors and consequences of youth violence, the authors apply RAT/LS theory to explain how community, family, peers, schools, and youth characteristics influence youth behavior. Each layer of the ecological framework unfolds to reveal the latest scholarship and contextualizes how concepts of RAT/LS, specifically the motivated offender, target suitability, and guardianship, can be applied at each level. This book also highlights the mechanisms and processes that contribute to youth exposure to and involvement in violence by exploring factors examined in the literature as protective and risk factors of youth violence. Youth violence occurs in context, and, as such, the understanding of multilevel predictors and preventive measures against it can be situated within an RAT/LS ecological framework. This work links theory to extant research. Ahlin and Antunes demonstrate how knowledge of youth violence can be used to develop a robust theoretical foundation that can inform policy to improve neighborhoods and youth experiences within their communities, families, and peers and within their schools while acknowledging the importance of individual characteristics. This monograph is essential reading for those interested in youth violence, juvenile delinquency, and juvenile justice research and anyone dedicated to preventing crime among youths.