Historically, it has been difficult to measure the impact of policies and programs designed to address juvenile crime. The most commonly used strategies for combating juvenile delinquency have primarily relied on intuition and fads. However, the promising research documented in "Changing Lives" presents methods that can directly remedy these deficiencies in our juvenile justice system. Peter W. Greenwood demonstrates here that as crime rates have fallen, researchers have identified connections between specific risk factors and criminal behavior. At the same time, program developers have discovered a wide array of innovative interventions. The result of all this activity has been the revelation of a few prevention models that reduce crime much more cost-effectively than popular approaches such as tougher sentencing, the D.A.R.E. campaign, boot camps, and "scared straight" programs. "Changing Lives" expertly presents the most promising of these prevention programs, their histories, the quality of evidence to support their effectiveness, the public policy programs involved in bringing them into wider use, and the potential for investments and developmental research to increase the range and quality of programs.