The National Longitudinal Survey of Adolescent Health (Add Health) was mandated by Congress to collect data for the purpose of measuring the impact of social environment on adolescent health. It examines the general health and well-being of adolescents in the United States, including, with respect to these adolescents, (1) the behaviors that promote health and the behaviors that are detrimental to health; and (2) the influence on health of factors particular to the communities in which adolescents reside. Dependent variables include diet and nutrition, eating disorders, depression, violent behavior, intentional injury, unintentional injury, suicide, exercise, health service use, and health insurance coverage.

Add Health was designed to assess the health status of adolescents and explore the causes of their healthrelated behaviors, focusing on the effects of the multiple contexts or environments (both social and physical) in which they live. This study has collected data of interest to investigators from many disciplines in the social and behavioral sciences and from many theoretical traditions.

The study explores the influences of both the individual attributes of adolescents and the attributes of their various environments on health and health-related behavior in areas such as diet, physical activity, health-service use, morbidity, injury, violence, sexual behavior, contraception, sexually transmitted infections, pregnancy, suicidal intentions/thoughts, substance use/abuse, and runaway behavior. Data were collected also on such attributes as height, weight, pubertal development, mental health status (focusing on depression, the most common mental health problem among adolescents), and chronic and disabling conditions.

Add Health is longitudinal, with adolescents interviewed for a second time at a one-year interval and a third time at a six-year interval. Rather than relying on respondents' memories and reconstructions of past events, this design makes it possible to measure directly the influence of their experiences at one time on their behavior, and its consequences, at another.