The National Longitudinal Study of Adolescent to Adult Health (Add Health) is a longitudinal study of a nationally representative sample of adolescents in grades 7-12 in the United States during the 1994-95 school year. The Add Health cohort has been followed into young adulthood with four in-home interviews, the most recent in 2008, when the sample was aged 24-32*. Add Health combines longitudinal survey data on respondents’ social, economic, psychological and physical well-being with contextual data on the family, neighborhood, community, school, friendships, peer groups, and romantic relationships, providing unique opportunities to study how social environments and behaviors in adolescence are linked to health and achievement outcomes in young adulthood. The fourth wave of interviews expanded the collection of biological data in Add Health to understand the social, behavioral, and biological linkages in health trajectories as the Add Health cohort ages through adulthood. The fifth wave of data collection is planned to begin in 2016.
Initiated in 1994 and supported by three program project grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) with co-funding from 23 other federal agencies and foundations, Add Health is the largest, most comprehensive longitudinal survey of adolescents ever undertaken. Beginning with an in-school questionnaire administered to a nationally representative sample of students in grades 7-12, the study followed up with a series of in-home interviews conducted in 1995, 1996, 2001-02, and 2008. Other sources of data include questionnaires for parents, siblings, fellow students, and school administrators and interviews with romantic partners. Preexisting databases provide information about neighborhoods and communities.
Add Health was developed in response to a mandate from the U.S. Congress to fund a study of adolescent health, and Waves I and II focus on the forces that may influence adolescents’ health and risk behaviors, including personal traits, families, friendships, romantic relationships, peer groups, schools, neighborhoods, and communities. As participants have aged into adulthood, however, the scientific goals of the study have expanded and evolved. Wave III, conducted when respondents were between 18 and 26** years old, focuses on how adolescent experiences and behaviors are related to decisions, behavior, and health outcomes in the transition to adulthood. At Wave IV, respondents were ages 24-32* and assuming adult roles and responsibilities. Follow up at Wave IV has enabled researchers to study developmental and health trajectories across the life course of adolescence into adulthood using an integrative approach that combines the social, behavioral, and biomedical sciences in its research objectives, design, data collection, and analysis.
* 52 respondents were 33-34 years old at the time of the Wave IV interview.
** 24 respondents were 27-28 years old at the time of the Wave III interview.
Included here are weights to remove any differences between the composition of the sample and the estimated composition of the population. See the attached codebook for information regarding how these weights were calculated.
- Data File
- Cases: 6,504
- See the following on-line document for details on weighting: Guidelines for Analyzing Add Health Data. To merge waves, use the merge variable "AID."
- Data Collection
- Date Collected: In-School Questionnaires (September 1994–April 1995) In-Home Interviews (April 1995–December 1995) Add Health Picture Vocabulary Test (April 1995–December 1995) Parent Questionnaires (April 1995–December 1995)
- Original Survey (Instrument)
- National Longitudinal Study of Adolescent Health, Public-use Grand Sample Weights, August 1998
- Funded By
- Department of Health and Human Services, National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health & Human Development, with cooperative funding from 23 other federal agencies and foundations.
- Collection Procedures
- In-school questionnaires, in-home interviews, Add Health Picture Vocabulary Test, and parent questionnaires
- Sampling Procedures
- Wave I consists of two samples: a school sample and an in-home sample. The school sample was a stratified, random sample of all high schools in the US. A school was eligible for the sample if it included an 11th grade and had a minimum enrollment of 30 students. A feeder school — a school that sent graduates to the high school and that included a seventh grade — was also recruited from the community. High schools were stratified into 80 clusters: Region — Northeast, Midwest, South, West; Urbanicity — urban, suburban, rural; School size — 125 or fewer, 126–350, 351–775, 776 or more students; School type — public, private, parochial; Percent white — 0, 1–66, 67–93, 94–100; Percent black — 0, 1–6, 7–33, 34–100; Grade span — K–12, 7–12, 9–12, 10–12; and Curriculum — general, vocational/technical, alternative, special education.
An in-home sample of 27,000 adolescents was drawn consisting of a core sample from each community plus selected special oversamples. Eligibility for oversamples was determined by an adolescent's responses on the In-School Questionnaire. Adolescents could qualify for more than one sample. In addition, parents were asked to complete a questionnaire about family and relationships. At Wave I, 20,745 of the 27,000 sampled adolescents agreed to participate and were interviewed. This public-use sample is a random sample of one-half of the in-home core sample and one-half of the in-home high education black oversample (adolescents with a parent with a college degree).
- Principal Investigators
- Dr. Kathleen Mullan Harris, Director, Add Health and James Haar, Distinguished Professor, Department of Sociology and Carolina Population Center Faculty Fellow, UNC-Chapel Hill
- Related Publications
- To access a publications database on the Add Health website, visit here, which includes more than 5,000 publications, presentations, unpublished manuscripts, and dissertations by Add Health researchers. To obtain a copy of any item, please contact the author.