This document is to provide clarity:  If the juvenile justice system is to achieve a reduction in recidivism through the prevention of delinquent behavior, it must adhere to the three principles of risk, need, and responsivity. A necessary first step in this process is the introduction and use of a valid and reliable assessment instrument, such as the Youth Level of Service/Case Management Inventory (YLS/CMI), to measure both a youth’s risk and needs.