This bulletin provides an overview of substance testing, describes major indicators of the need for such testing, and summarizes the research for recent trends in substance abuse. It examines the practices of implementing a policy of controlled substance testing for appropriate categories of juveniles within the juvenile justice system. A summary is provided of key decisions and steps that must be taken to develop a program of controlled substance testing and to help select the appropriate categories of juveniles to test. Recent trends in substance abuse among youth are presented and the major indicators of the need for substance testing are explained. Several of the consequences of substance abuse among youth are delineated such as school problems; health and safety consequences; peer relationships complications; family issues; and social and economic costs. Key elements of implementing a program of substance testing are described and examples of substance-testing programs in a variety of juvenile justice agencies are included. The most important ingredient of a substance-testing program is the intervening that needs to occur after testing to help stop youth from using controlled substances. A list of references for program contacts, suggested readings, and addresses of organizations are included. (Contains 20 references.) (JDM)