This report analyzes practices and conditions that seek to prevent at-risk behaviors among adolescents. Discussion begins with a description of the developmental tasks that adolescents need to complete before they can assume productive adult roles in society. While two conflicting views of adolescence are noted, the capacity of young people to change is supported. The report examines characteristics of home, school, and community environments that support the healthy physical, emotional, social, cognitive, and character development of adolescents. The report then outlines a process for identifiying at-risk adolescents and highlights some intervention designs for youths already displaying at-risk behaviors. Interventions include academic support, pupil services and social services supports, career preparation and experiential learning, schools of choice, and school reorganization. Concluding discussion concerns two challenges to those attempting to make changes that will benefit high school students. For each challenge, barriers that will need to be dealt with are listed. Forty-three profiles of intervention programs that serve as examples across the nation are appended. A list of 65 references is provided. (RH)