This case study discusses some common problems of crime measurement within the context of secondary data analysis. An investigation into possible reasons behind the falling crime rates is used as a backdrop to illustrate how crime trends can be measured at the state level. One promising explanation for the declines in juvenile delinquency and violence has been tested in the research project described: the increased prescribing of psychotropic medications to children and adolescents. The case study focuses on the dependent variables for this project: changes in juvenile delinquency and violence at the state level. Several possible ways of measuring juvenile delinquency and violence are discussed, with a focus on official sources of data (Uniform Crime Reports arrests, Supplementary Homicide Reports, Vital Statistics) and their applicability and limitations. Besides official statistics, the other two common sources of crime data are also discussed: victimization reports (National Crime Victimization Survey) and self-reports (Monitoring the Future, Youth Risk Behavior Surveillance System). The project findings are briefly described as well: it turns out that the consumption of psychotropic medications does not seem to be related to the trends in juvenile delinquency or violent outcomes. Instead, child poverty and school services to students with disabilities emerge as two powerful factors related to youth violence: child poverty increases later violence, whereas school-based services to students with learning disabilities decrease violent outcomes.